NAME

CGI::Ex::Template - Fast and lightweight TT2/3 template engine

SYNOPSIS

### Template::Toolkit style usage

my $t = CGI::Ex::Template->new(
    INCLUDE_PATH => ['/path/to/templates'],
);

my $swap = {
    key1 => 'val1',
    key2 => 'val2',
    code => sub { 42 },
    hash => {a => 'b'},
};

# print to STDOUT
$t->process('my/template.tt', $swap)
    || die $t->error;

# process into a variable
my $out = '';
$t->process('my/template.tt', $swap, \$out);

### CET uses the same syntax and configuration as Template::Toolkit


### HTML::Template style usage

my $t = CGI::Ex::Template->new(
    filename => 'my/template.ht',
    path     => ['/path/to/templates'],
);

my $swap = {
    key1 => 'val1',
    key2 => 'val2',
    code => sub { 42 },
    hash => {a => 'b'},
};

$t->param($swap);

# print to STDOUT (errors die)
$t->output(print_to => \*STDOUT);

# process into a variable
my $out = $t->output;

### CET can also use the same syntax and configuration as HTML::Template

DESCRIPTION

CGI::Ex::Template happened by accident (accidentally on purpose). The CGI::Ex::Template (CET hereafter) was originally a part of the CGI::Ex suite that performed simple variable interpolation. It used TT2 style variables in TT2 style tags "[% foo.bar %]". That was all the original CGI::Ex::Template did. This was fine and dandy for a couple of years. In winter of 2005-2006 CET was revamped to add a few features. One thing led to another and soon CET provided for most of the features of TT2 as well as some from TT3. CGI::Ex::Template is a full-featured implementation of the Template::Toolkit language.

As of version 2.13, CGI::Ex::Template also provides near full compatibility with HTML::Template (HT), HTML::Template::JIT (HTJ), and HTML::Template::Expr (HTE). Version 2.13 introduced the SYNTAX configuration allowing for inclusion of TT style templates in HT and vice versa. It also provided the HTML::Template output and param methods which allow CET to provide the HTML::Template interface. It was possible to add this extra functionality because CGI::Ex::Template employs an open architecture.

CGI::Ex::Template uses a recursive regex based grammar (early versions before the 2.10 release did not). This allows for the embedding of opening and closing tags inside other tags (as in [% a = "[% 1 + 2 %]" ; a|eval %]). The individual methods such as parse_expr and play_expr may be used by external applications to add TT style variable parsing to other applications.

CGI::Ex::Template is fast but CGI::Ex::Template::XS is even faster. If CGI::Ex::Template isn't fast enough for you, the XS version has key methods coded in C and provides a noticable improvement over the non-XS version. CET by itself is generally faster than TT, HT, and HTE. The XS version is nearly always faster - even than HTJ. CET also uses less memory than TT and HTE, and only a little more than HT. (This is all as of version 2.13 in May 2007 - those other modules will undoubtedly receive updates that will improve their performance).

Most of the standard Template::Toolkit documentation covering directives, variables, configuration, plugins, filters, syntax, and vmethods should apply to CET just fine (This pod tries to explain everything - but there is too much). The section on differences between CET and TT will explain what too look out for.

Additionally, most of the standard HTML::Template and HTML::Template::Expr documentation covering methods, variables, expressions, and syntax will apply to CET just fine as well.

So should you use CGI::Ex::Template ? Well, try it out. It may give you no visible improvement. Or it could.

PUBLIC METHODS

The following section lists most of the publicly available methods. Some less commonly used public methods are listed later in this document.

new

my $obj = CGI::Ex::Template->new({
    INCLUDE_PATH => ['/my/path/to/content', '/my/path/to/content2'],
});

Arguments may be passed as a hash or as a hashref. Returns a CGI::Ex::Template object.

There are currently no errors during CGI::Ex::Template object creation. If you are using the HTML::Template interface, this is different behavior. The document is not parsed until the output or process methods are called.

process

This is the main method call for starting processing. Any errors that result in the template processing being stopped will be stored and available via the ->error method. This is the TT compatible method - see the output method for HT compatibility.

my $t = CGI::Ex::Template->new;
$t->process($in, $swap, $out)
    || die $t->error;

Process takes three arguments.

The $in argument can be any one of:

String containing the filename of the template to be processed.  The filename should
be relative to INCLUDE_PATH.  (See INCLUDE_PATH, ABSOLUTE, and RELATIVE configuration items).
In memory caching and file side caching are available for this type.

A reference to a scalar containing the contents of the template to be processed.

A coderef that will be called to return the contents of the template.

An open filehandle that will return the contents of the template when read.

The $swap argument should be hashref containing key value pairs that will be available to variables swapped into the template. Values can be hashrefs, hashrefs of hashrefs and so on, arrayrefs, arrayrefs of arrayrefs and so on, coderefs, objects, and simple scalar values such as numbers and strings. See the section on variables.

The $out argument can be any one of:

undef - meaning to print the completed template to STDOUT.

String containing a filename.  The completed template will be placed in the file.

A reference to a string.  The contents will be appended to the scalar reference.

A coderef.  The coderef will be called with the contents as a single argument.

An object that can run the method "print".  The contents will be passed as
a single argument to print.

An arrayref.  The contents will be pushed onto the array.

An open filehandle.  The contents will be printed to the open handle.

Additionally - the $out argument can be configured using the OUTPUT configuration item.

The process method defaults to using the "cet" syntax which will parse TT3 and most TT2 documents. To parse HT or HTE documents, you must pass the SYNTAX configuration item to the "new" method. All calls to process would then default to HTE syntax.

my $obj = CGI::Ex::Template->new(SYNTAX => 'hte');

process_simple

Similar to the process method but with the following restrictions:

The $in parameter is limited to a filename or a reference a string containing the contents.

The $out parameter may only be a reference to a scalar string that output will be appended to.

Additionally, the following configuration variables will be ignored: VARIABLES, PRE_DEFINE, BLOCKS, PRE_PROCESS, PROCESS, POST_PROCESS, AUTO_RESET, OUTPUT.

error

Should something go wrong during a "process" command, the error that occurred can be retrieved via the error method.

$obj->process('somefile.html', {a => 'b'}, \$string_ref)
    || die $obj->error;

output

HTML::Template way to process a template. The output method requires that a filename, filehandle, scalarref, or arrayref argument was passed to the new method. All of the HT calling conventions for new are supported. The key difference is that CET will not actually process the template until the output method is called.

my $obj = CGI::Ex::Template->new(filename => 'myfile.html');
$obj->param(\%swap);
print $obj->output;

See the HTML::Template documentation for more information.

The output method defaults to using the "hte" syntax which will parse HTE and HT documents. To parse TT3 or TT2 documents, you must pass the SYNTAX configuration item to the "new" method. All calls to process would then default to TT3 syntax.

my $obj = CGI::Ex::Template->new(SYNTAX => 'tt3');

Any errors that occur during the output method will die with the error as the die value.

param

HTML::Template way to get or set variable values that will be used by the output method.

my $val = $obj->param('key'); # get one value

$obj->param(key => $val);     # set one value

$obj->param(key => $val, key2 => $val2);   # set multiple

$obj->param({key => $val, key2 => $val2}); # set multiple

See the HTML::Template documentation for more information.

Note: CET does not support the die_on_bad_params configuration. This is because CET does not resolve variable names until the output method is called.

define_vmethod

This method is available for defining extra Virtual methods or filters. This method is similar to Template::Stash::define_vmethod.

CGI::Ex::Template->define_vmethod(
    'text',
    reverse => sub { my $item = shift; return scalar reverse $item },
);

register_function

This is the HTML::Template way of defining text vmethods. It is the same as calling define_vmethod with "text" as the first argument.

CGI::Ex::Template->register_function(
    reverse => sub { my $item = shift; return scalar reverse $item },
);

define_directive

This method can be used for adding new directives or overridding existing ones.

CGI::Ex::Template->define_directive(
    MYDIR => {
        parse_sub => sub {}, # parse additional items in the tag
        play_sub  => sub {
            my ($self, $ref, $node, $out_ref) = @_;
            $$out_ref .= "I always say the same thing!";
            return;
        },
        is_block  => 1,  # is this block like
        is_postop => 0,  # not a post operative directive
        no_interp => 1,  # no interpolation in this block
        continues => undef, # it doesn't "continue" any other directives
    },
);

Now with a template like:

my $str = "([% MYDIR %]This is something[% END %])";
CGI::Ex::Template->new->process(\$str);

You will get:

(I always say the same thing!)

We'll add more details in later revisions of this document.

define_syntax

This method can be used for adding other syntaxes to or overridding existing ones in the list of choices available in CET. The syntax can be chosen by the SYNTAX configuration item.

CGI::Ex::Template->define_syntax(
    my_uber_syntax => sub {
        my $self = shift;
        local $self->{'V2PIPE'}      = 0;
        local $self->{'V2EQUALS'}    = 0;
        local $self->{'PRE_CHOMP'}   = 0;
        local $self->{'POST_CHOMP'}  = 0;
        local $self->{'NO_INCLUDES'} = 0;
        return $self->parse_tree_tt3(@_);
    },
);

The subroutine that is used must return an opcode tree (AST) that can be played by the execute_tree method.

define_operator

This method allows for adding new operators or overriding existing ones.

CGI::Ex::Template->define_operator({
    type       => 'right', # can be one of prefix, postfix, right, left, none, ternary, assign
    precedence => 84,      # relative precedence for resolving multiple operators without parens
    symbols    => ['foo', 'FOO'], # any mix of chars can be used for the operators
    play_sub   => sub {
        my ($one, $two) = @_;
        return "You've been foo'ed ($one, $two)";
    },
});

You can then use it in a template as in the following:

my $str = "[% 'ralph' foo 1 + 2 * 3 %]";
CGI::Ex::Template->new->process(\$str);

You will get:

You've been foo'ed (ralph, 7)

Future revisions of this document will include more samples.

TODO

Move module to its own namespace.

Cleanup operator API to allow for easier full customization of operators.

Give better examples of overriding directives, syntax, and operators.

Add more functions to the XS version.

Find other syntaxes to include.

HOW IS CGI::Ex::Template DIFFERENT from Template::Toolkit

CET uses the same base template syntax and configuration items as TT2, but the internals of CET were written from scratch. Additionally much of the planned TT3 syntax is supported as well as most of that of HTML::Template::Expr. The following is a list of some of the ways that the configuration and syntax of CET are different from that of TT2. Note: items that are planned to work in TT3 are marked with (TT3).

Numerical hash keys work
```
[% a = {1 => 2} %]
```
Quoted hash key interpolation is fine
```
[% a = {"$foo" => 1} %]
```
Multiple ranges in same constructor
```
[% a = [1..10, 21..30] %]
```

Constructor types can call virtual methods. (TT3)

[% a = [1..10].reverse %]

[% "$foo".length %]

[% 123.length %]   # = 3

[% 123.4.length %]  # = 5

[% -123.4.length %] # = -5 ("." binds more tightly than "-")

[% (a ~ b).length %]

[% "hi".repeat(3) %] # = hihihi

[% {a => b}.size %] # = 1

The "${" and "}" variable interpolators can contain expressions, not just variables.

[% [0..10].${ 1 + 2 } %] # = 4

[% {ab => 'AB'}.${ 'a' ~ 'b' } %] # = AB

[% color = qw/Red Blue/; FOR [1..4] ; color.${ loop.index % color.size } ; END %]
  # = RedBlueRedBlue

You can use regular expression quoting.

[% "foo".match( /(F\w+)/i ).0 %] # = foo

Tags can be nested.

[% f = "[% (1 + 2) %]" %][% f|eval %] # = 3

Arrays can be accessed with non-integer numbers.
```
[% [0..10].${ 2.3 } %] # = 3
```

Reserved names are less reserved. (TT3)

[% GET GET %] # gets the variable named "GET"

[% GET $GET %] # gets the variable who's name is stored in "GET"

Filters and SCALAR_OPS are interchangeable. (TT3)
```
[% a | length %]

[% b . lower %]
```

Pipe "|" can be used anywhere dot "." can be and means to call the virtual method. (TT3)

[% a = {size => "foo"} %][% a.size %] # = foo

[% a = {size => "foo"} %][% a|size %] # = 1 (size of hash)

Pipe "|" and "." can be mixed. (TT3)
```
[% "aa" | repeat(2) . length %] # = 4
```
Added V2PIPE configuration item

Restores the behavior of the pipe operator to be compatible with TT2.

With V2PIPE = 1
```
[% PROCESS a | repeat(2) %] # = value of block or file a repeated twice
```
With V2PIPE = 0 (default)
```
[% PROCESS a | repeat(2) %] # = process block or file named a ~ a
```
Added V2EQUALS configuration item

Allows for turning off TT2 "==" behavior. Defaults to 1 in TT syntaxes and to 0 in HT syntaxes.
```
[% CONFIG V2EQUALS => 1 %][% ('7' == '7.0') || 0 %]
[% CONFIG V2EQUALS => 0 %][% ('7' == '7.0') || 0 %]
```
Prints
```
0
1
```

Added Virtual Object Namespaces. (TT3)

The Text, List, and Hash types give direct access to virtual methods.

[% a = "foobar" %][% Text.length(a) %] # = 6

[% a = [1 .. 10] %][% List.size(a) %] # = 10

[% a = {a=>"A", b=>"B"} ; Hash.size(a) %] = 2

[% foo = {a => 1, b => 2}
   | Hash.keys
   | List.join(", ") %] # = a, b

Added "fmt" scalar, list, and hash virtual methods.

[% list.fmt("%s", ", ") %]

[% hash.fmt("%s => %s", "\n") %]

Added missing HTML::Template::Expr vmethods

The following vmethods were added - they correspond to the perl functions of the same name.
```
abs
atan2
cos
exp
hex
lc
log
oct
sin
sprintf
sqrt
srand
uc
```
Allow all Scalar vmethods to behave as top level functions.
```
[% sprintf("%d %d", 7, 8) %] # = "7 8"
```
The following are equivalent in CET:
```
[% "abc".length %]
[% length("abc") %]
```
This feature may be disabling by setting the VMETHOD_FUNCTIONS configuration item to 0.

This is similar to how HTML::Template::Expr operates, but now you can use this functionality in TT templates as well.
Whitespace is less meaningful. (TT3)
```
[% 2-1 %] # = 1 (fails in TT2)
```
Added pow operator.
```
[% 2 ** 3 %] [% 2 pow 3 %] # = 8 8
```
Added string comparison operators (gt ge lt le cmp)
```
[% IF "a" lt "b" %]a is less[% END %]
```
Added numeric comparison operator (<=>)

This can be used to make up for the fact that TT2 made == the same as eq (which will hopefully change - use eq when you mean eq).
```
[% IF ! (a <=> b) %]a == b[% END %]

[% IF (a <=> b) %]a != b[% END %]
```

Added self modifiers (+=, -=, *=, /=, %=, **=, ~=). (TT3)

[% a = 2;  a *= 3  ; a %] # = 6
[% a = 2; (a *= 3) ; a %] # = 66

Added pre and post increment and decrement (++ --). (TT3)
```
[% ++a ; ++a %] # = 12
[% a-- ; a-- %] # = 0-1
```

Added qw// contructor. (TT3)

[% a = qw(a b c); a.1 %] # = b

[% qw/a b c/.2 %] # = c

Added regex contructor. (TT3)

[% "FOO".match(/(foo)/i).0 %] # = FOO

[% a = /(foo)/i; "FOO".match(a).0 %] # = FOO

Allow for scientific notation. (TT3)

[% a = 1.2e-20 %]

[% 123.fmt('%.3e') %] # = 1.230e+02

Allow for hexidecimal input. (TT3)

[% a = 0xff0000 %][% a %] # = 16711680

[% a = 0xff2 / 0xd; a.fmt('%x') %] # = 13a

FOREACH variables can be nested.
```
[% FOREACH f.b = [1..10] ; f.b ; END %]
```
Note that nested variables are subject to scoping issues. f.b will not be reset to its value before the FOREACH.

Post operative directives can be nested. (TT3)

Andy Wardley calls this side-by-side effect notation.

[% one IF two IF three %]

same as

[% IF three %][% IF two %][% one %][% END %][% END %]


[% a = [[1..3], [5..7]] %][% i FOREACH i = j FOREACH j = a %] # = 123567

Semi-colons on directives in the same tag are optional. (TT3)
```
[% SET a = 1
   GET a
 %]

[% FOREACH i = [1 .. 10]
     i
   END %]
```
Note: a semi-colon is still required in front of any block directive that can be used as a post-operative directive.
```
[% 1 IF 0
   2 %]   # prints 2

[% 1; IF 0
   2
   END %] # prints 1
```
Note2: This behavior can be disabled by setting the SEMICOLONS configuration item to a true value. If SEMICOLONS is true, then a SEMICOLON must be set after any directive that isn't followed by a post-operative directive.
CATCH blocks can be empty.

TT2 requires them to contain something.
Added a DUMP directive.

Used for Data::Dumpering the passed variable or expression.
```
[% DUMP a.a %]
```

Added CONFIG directive.

[% CONFIG
     ANYCASE   => 1
     PRE_CHOMP => '-'
%]

Configuration options can use lowercase names instead of the all uppercase names that TT2 uses.
```
my $t = CGI::Ex::Template->new({
    anycase     => 1,
    interpolate => 1,
});
```

Added LOOP directive (works the same as LOOP in HTML::Template.

[%- var = [{key => 'a'}, {key => 'b'}] %]
[%- LOOP var %]
  ([% key %])
[%- END %]

Prints

  (a)
  (b)

CET can parse HTML::Template and HTML::Template::Expr documents as well as TT2 and TT3 documents.
Added SYNTAX configuration. The SYNTAX configuration can be used to change what template syntax will be used for parsing included templates or eval'ed strings.
```
[% CONFIG SYNTAX => 'hte' %]
[% var = '<TMPL_VAR EXPR="sprintf('%s', 'hello world')">' %]
[% var | eval %]
```
CET does not generate Perl code.

It generates an "opcode" tree. The opcode tree is an arrayref of scalars and array refs nested as deeply as possible. This "simple" structure could be shared TT implementations in other languages via JSON or YAML.
CET uses storable for its compiled templates.

If EVAL_PERL is off, CET will not eval_string on ANY piece of information.
There is eval_filter and MACRO recursion protection

You can control the nested nature of eval_filter and MACRO recursion using the MAX_EVAL_RECURSE and MAX_MACRO_RECURSE configuration items.
There is no context.

CET provides a context object that mimics the Template::Context interface for use by some TT filters, eval perl blocks, views, and plugins.
There is no stash.

Well there is but it isn't an object.

CET only supports the variables passed in VARIABLES, PRE_DEFINE, and those passed to the process method. CET provides a stash object that mimics the Template::Stash interface for use by some TT filters, eval perl blocks, and plugins.
There is no provider.

CET uses the load_parsed_tree method to get and cache templates.
There is no parser/grammar.

CET has its own built-in recursive regex based parser and grammar system.

CET can actually be substituted in place of the native Template::Parser and Template::Grammar in TT by using the Template::Parser::CET module. This module uses the output of parse_tree to generate a TT style compiled perl document.
The DEBUG directive is more limited.

It only understands DEBUG_DIRS (8) and DEBUG_UNDEF (2).
CET has better line information

When debug dirs is on, directives on different lines separated by colons show the line they are on rather than a general line range.

Parse errors actually know what line and character they occured at.

HOW IS CGI::Ex::Template DIFFERENT from HTML::Template

CET can use the same base template syntax and configuration items as HTE and HT. The internals of CET were written to support TT3, but were general enough to be extended to support HTML::Template as well. The result is HTML::Template::Expr compatible syntax, with CET speed and a wide range of additional features.

The TMPL_VAR, TMPL_IF, TMPL_ELSE, TMPL_UNLESS, TMPL_LOOP, and TMPL_INCLUDE all work identically to HTML::Template.

Added support for other TT3 directives and for TT style "dot notation."
```
<TMPL_SET a = "bar">
<TMPL_SET b = [1 .. 25]>
<TMPL_SET foo = PROCESS 'filename.tt'>

<TMPL_GET foo>  # similar to <TMPL_VAR NAME="foo">
<TMPL_GET b.3>
<TMPL_GET my.nested.chained.variable.1>
<TMPL_GET my_var | html>

<TMPL_USE foo = DBI(db => ...)>
<TMPL_CALL foo.connect>
```
Any of the TT directives can be used in HTML::Template documents.

For many die-hard HTML::Template fans, it is probably quite scary to be providing all of the TT functionality. All of the extended TT functionality can be disabled by setting the NO_TT configuration item. The NO_TT configuration is automatically set if the SYNTAX is set to "ht" and the output method is called.

There is an ELSIF!!!

<TMPL_IF foo>
  FOO
<TMPL_ELSIF bar>
  BAR
<TMPL_ELSE>
  Done then
</TMPL_IF>

Added CHOMP capabilities (PRE_CHOMP and POST_CHOMP)
```
Foo
<~TMPL_VAR EXPR="1+2"~>
Bar

Prints Foo3Bar
```

Added INTERPOLATE capability

<TMPL_SET foo = 'FOO'>
<TMPL_CONFIG INTERPOLATE => 1>
$foo <TMPL_GET foo> ${ 1 + 2 }

Prints

FOO FOO 3

Allow for HTML::Template templates to include TT style templates.
```
<TMPL_CONFIG SYNTAX => 'tt3'>
<TMPL_INCLUDE "filename.tt">
```
Allow for Expr parsing to follow proper precedence rules.
```
<TMPL_VAR EXPR="1 + 2 * 3">

Properly prints 7.
```
Uses all of the caching and opcode tree optimations provided by CGI::Ex::Template and CGI::Ex::Template::XS.
CET does not provide the query method from HTML::Template. This is because parsing of the document is delayed until the output method is called, and because CET supports TT style chained variables which often are not resolvable until run time.

VARIABLES

This section discusses how to use variables and expressions in the TT mini-language.

A variable is the most simple construct to insert into the TT mini language. A variable name will look for the matching value inside CGI::Ex::Templates internal stash of variables which is essentially a hash reference. This stash is initially populated by either passing a hashref as the second argument to the process method, or by setting the "VARIABLES" or "PRE_DEFINE" configuration variables.

If you are using the HT and HTE syntaxes, the VAR, IF, UNLESS, LOOP, and INCLUDE directives will accept a NAME attribute which may only be a single level (non-chained) HTML::Template variable name, or they may accept an EXPR attribute which may be any valid TT3 variable or expression.

The following are some sample ways to access variables.

### some sample variables
my %vars = (
    one       => '1.0',
    foo       => 'bar',
    vname     => 'one',
    some_code => sub { "You passed me (".join(', ', @_).")" },
    some_data => {
        a     => 'A',
        bar   => 3234,
        c     => [3, 1, 4, 1, 5, 9],
        vname => 'one',
    },
    my_list   => [20 .. 50],
    cet       => CGI::Ex::Template->new,
);

### pass the variables into the CET process
$cet->process($template_name, \%vars)
     || die $cet->error;

### pass the variables during object creation (will be available to every process call)
my $cet = CGI::Ex::Template->new(VARIABLES => \%vars);

GETTING VARIABLES

Once you have variables defined, they can be used directly in the template by using their name in the stash. Or by using the GET directive.

[% foo %]
[% one %]
[% GET foo %]

Would print when processed:

bar
1.0
bar

To access members of a hashref or an arrayref, you can chain together the names using a ".".

[% some_data.a %]
[% my_list.0] [% my_list.1 %] [% my_list.-1 %]
[% some_data.c.2 %]

Would print:

A
20 21 50
4

If the value of a variable is a code reference, it will be called. You can add a set of parenthesis and arguments to pass arguments. Arguments are variables and can be as complex as necessary.

[% some_code %]
[% some_code() %]
[% some_code(foo) %]
[% some_code(one, 2, 3) %]

Would print:

You passed me ().
You passed me ().
You passed me (bar).
You passed me (1.0, 2, 3).

If the value of a variable is an object, methods can be called using the "." operator.

[% cet %]

[% cet.dump_parse_expr('1 + 2').replace('\s+', ' ') %]

Would print something like:

CGI::Ex::Template=HASH(0x814dc28)

$VAR1 = [ [ undef, '+', '1', '2' ], 0 ];

Each type of data (string, array and hash) have virtual methods associated with them. Virtual methods allow for access to functions that are commonly used on those types of data. For the full list of built in virtual methods, please see the section titled VIRTUAL METHODS

[% foo.length %]
[% my_list.size %]
[% some_data.c.join(" | ") %]

Would print:

3
31
3 | 1 | 4 | 5 | 9

It is also possible to "interpolate" variable names using a "$". This allows for storing the name of a variable inside another variable. If a variable name is a little more complex it can be embedded inside of "${" and "}".

[% $vname %]
[% ${vname} %]
[% ${some_data.vname} %]
[% some_data.$foo %]
[% some_data.${foo} %]

Would print:

In CET it is also possible to embed any expression (non-directive) in "${" and "}" and it is possible to use non-integers for array access. (This is not available in TT2)

[% ['a'..'z'].${ 2.3 } %]
[% {ab => 'AB'}.${ 'a' ~ 'b' } %]
[% color = qw/Red Blue/; FOR [1..4] ; color.${ loop.index % color.size } ; END %]

Would print:

c
AB
RedBlueRedBlue

SETTING VARIABLES.

To define variables during processing, you can use the = operator. In most cases this is the same as using the SET directive.

[% a = 234 %][% a %]
[% SET b = "Hello" %][% b %]

Would print:

234
Hello

It is also possible to create arrayrefs and hashrefs.

[% a = [1, 2, 3] %]
[% b = {key1 => 'val1', 'key2' => 'val2'} %]

[% a.1 %]
[% b.key1 %] [% b.key2 %]

Would print:

2
val1 val2

It is possible to set multiple values in the same SET directive.

[% SET a = 'A'
       b = 'B'
       c = 'C' %]
[% a %]    [% b %]    [% c %]

Would print:

A    B    C

It is also possible to unset variables, or to set members of nested data structures.

[% a = 1 %]
[% SET a %]

[% b.0.c = 37 %]

([% a %])
[% b.0.c %]

Would print

()
37

LITERALS AND CONSTRUCTORS

The following are the types of literals (numbers and strings) and constructors (hash and array constructs) allowed in CET. They can be used as arguments to functions, in place of variables in directives, and in place of variables in expressions. In CET it is also possible to call virtual methods on literal values.

Integers and Numbers.

[% 23423   %]        Prints an integer.
[% 3.14159 %]        Prints a number.
[% pi = 3.14159 %]   Sets the value of the variable.
[% 3.13159.length %] Prints 7 (the string length of the number)

Scientific notation is supported.

[% 314159e-5 + 0 %]      Prints 3.14159.

[% .0000001.fmt('%.1e') %]  Prints 1.0e-07

Hexidecimal input is also supported.

[% 0xff + 0 %]    Prints 255

[% 48875.fmt('%x') %]  Prints beeb

Single quoted strings.

Returns the string. No variable interpolation happens.

[% 'foobar' %]          Prints "foobar".
[% '$foo\n' %]          Prints "$foo\\n".  # the \\n is a literal "\" and an "n"
[% 'That\'s nice' %]    Prints "That's nice".
[% str = 'A string' %]  Sets the value of str.
[% 'A string'.split %]  Splits the string on ' ' and returns the list.

Note: virtual methods can only be used on literal strings in CET, not in TT.

You may also embed the current tags in strings (CET only).

[% '[% 1 + 2 %]' | eval %]  Prints "3"

Double quoted strings.

Returns the string. Variable interpolation happens.

[% "foobar" %]                   Prints "foobar".
[% "$foo"   %]                   Prints "bar" (assuming the value of foo is bar).
[% "${foo}" %]                   Prints "bar" (assuming the value of foo is bar).
[% "foobar\n" %]                 Prints "foobar\n".  # the \n is a newline.
[% str = "Hello" %]              Sets the value of str.
[% "foo".replace('foo','bar') %] Prints "bar".

Note: virtual methods can only be used on literal strings in CET, not in TT.

You may also embed the current tags in strings (CET only).

[% "[% 1 + 2 %]" | eval %]  Prints "3"

Array Constructs.

[% [1, 2, 3] %]               Prints something like ARRAY(0x8309e90).
[% array1 = [1 .. 3] %]       Sets the value of array1.
[% array2 = [foo, 'a', []] %] Sets the value of array2.
[% [4, 5, 6].size %]          Prints 3.
[% [7, 8, 9].reverse.0 %]     Prints 9.

Note: virtual methods can only be used on array contructs in CET, not in TT.

Quoted Array Constructs.

[% qw/1 2 3/ %]                Prints something like ARRAY(0x8309e90).
[% array1 = qw{Foo Bar Baz} %] Sets the value of array1.
[% qw[4 5 6].size %]           Prints 3.
[% qw(Red Blue).reverse.0 %]   Prints Blue.

Note: this works in CET and is planned for TT3.

Hash Constructs.

[% {foo => 'bar'} %]                 Prints something like HASH(0x8305880)
[% hash = {foo => 'bar', c => {}} %] Sets the value of hash.
[% {a => 'A', b => 'B'}.size %]      Prints 2.
[% {'a' => 'A', 'b' => 'B'}.size %]  Prints 2.
[% name = "Tom" %]
[% {Tom => 'You are Tom',
    Kay => 'You are Kay'}.$name %]   Prints You are Tom

Note: virtual methods can only be used on hash contructs in CET, not in TT.

Regex Constructs.

[% /foo/ %]                              Prints (?-xism:foo)
[% a = /(foo)/i %][% "FOO".match(a).0 %] Prints FOO

Note: this works in CET and is planned for TT3.

EXPRESSIONS

Expressions are one or more variables or literals joined together with operators. An expression can be used anywhere a variable can be used with the exception of the variable name in the SET directive, and the filename of PROCESS, INCLUDE, WRAPPER, and INSERT.

The following section shows some samples of expressions. For a full list of available operators, please see the section titled OPERATORS.

[% 1 + 2 %]           Prints 3
[% 1 + 2 * 3 %]       Prints 7
[% (1 + 2) * 3 %]     Prints 9

[% x = 2 %]                      # assignments don't return anything
[% (x = 2) %]         Prints 2   # unless they are in parens
[% y = 3 %]
[% x * (y - 1) %]     Prints 4

VIRTUAL METHODS

The following is the list of builtin virtual methods and filters that can be called on each type of data.

In CGI::Ex::Template, the "|" operator can be used to call virtual methods just the same way that the "." operator can. The main difference between the two is that on access to hashrefs or objects, the "|" means to always call the virtual method or filter rather than looking in the hashref for a key by that name, or trying to call that method on the object. This is similar to how TT3 will function.

Virtual methods are also made available via Virtual Objects which are discussed in a later section.

SCALAR VIRTUAL METHODS AND FILTERS

The following is the list of builtin virtual methods and filters that can be called on scalar data types. In CET and TT3, filters and virtual methods are more closely related than in TT2. In general anywhere a virtual method can be used a filter can be used also - and likewise all scalar virtual methods can be used as filters.

In addition to the filters listed below, CET will automatically load Template::Filters and use them if Template::Toolkit is installed.

In addition to the scalar virtual methods, any scalar will be automatically converted to a single item list if a list virtual method is called on it.

Scalar virtual methods are also available through the "Text" virtual object (except for true filters such as eval and redirect).

All scalar virtual methods are available as top level functions as well. This is not true of TT2. In CGI::Ex::Template the following are equivalent:

[% "abc".length %]
[% length("abc") %]

You may set VMETHOD_FUNCTIONS to 0 to disable this behavior.

'0'

[% item = 'foo' %][% item.0 %] Returns foo.

Allows for scalars to mask as arrays (scalars already will, but this allows for more direct access).

abs

[% -1.abs %] Returns the absolute value

atan2

[% pi = 4 * 1.atan2(1) %]

Returns the arctangent. The item itself represents Y, the passed argument represents X.

chunk

[% item.chunk(60).join("\n") %] Split string up into a list of chunks of text 60 chars wide.

collapse

[% item.collapse %] Strip leading and trailing whitespace and collapse all other space to one space.

cos

[% item.cos %] Returns the cosine of the item.

defined

[% item.defined %] Always true - because the undef sub translates all undefs to ''.

eval

[% item.eval %]

Process the string as though it was a template. This will start the parsing engine and will use the same configuration as the current process. CET is several times faster at doing this than TT is and is considered acceptable.

This is a filter and is not available via the Text virtual object.

evaltt

Same as the eval filter.

exp

[% 1.exp %] Something like 2.71828182845905

Returns "e" to the power of the item.

file

Same as the redirect filter.

fmt

[% item.fmt('%d') %]
[% item.fmt('%6s') %]
[% item.fmt('%*s', 6) %]

Similar to format. Returns a string formatted with the passed pattern. Default pattern is %s. Opposite from of the sprintf vmethod.

format

[% item.format('%d') %]
[% item.format('%6s') %]
[% item.format('%*s', 6) %]

Print the string out in the specified format. It is similar to the "fmt" virtual method, except that the item is split on newline and each line is processed separately.

hash

[% item.hash %] Returns a one item hash with a key of "value" and a value of the item.

hex

[% "FF".hex %]

Returns the decimal value of the passed hex numbers. Note that you may also just use [% 0xFF %].

html

[% item.html %] Performs a very basic html encoding (swaps out &, <, > and " for the html entities)

indent

[% item.indent(3) %] Indent that number of spaces.

[% item.indent("Foo: ") %] Add the string "Foo: " to the beginning of every line.

int

[% item.int %] Return the integer portion of the value (0 if none).

lc

Same as the lower vmethod. Returns the lower cased version of the item.

lcfirst

[% item.lcfirst %] Capitalize the leading letter.

length

[% item.length %] Return the length of the string.

list

[% item.list %] Returns a list with a single value of the item.

log

[% 8.exp.log %] Equal to 8.

Returns the natural log base "e" of the item.

lower

[% item.lower %] Return a lower-casified string.

match

[% item.match("(\w+) (\w+)") %] Return a list of items matching the pattern.

[% item.match("(\w+) (\w+)", 1) %] Same as before - but match globally.

In CGI::Ex::Template and TT3 you can use regular expressions notation as well.

[% item.match( /(\w+) (\w+)/ ) %] Same as before.

[% item.match( m{(\w+) (\w+)} ) %] Same as before.

null

[% item.null %] Do nothing.

oct

[% "377".oct %]

Returns the decimal value of the octal string. On recent versions of perl you may also pass numbers starting with 0x which will be interpreted as hexidecimal, and starting with 0b which will be interpreted as binary.

rand

[% item = 10; item.rand %] Returns a number greater or equal to 0 but less than 10.
[% 1.rand %]

Note: This filter is not available as of TT2.15.

remove

[% item.remove("\s+") %] Same as replace - but is global and replaces with nothing.

redirect

[% item.redirect("output_file.html") %]

Writes the contents out to the specified file. The filename must be relative to the OUTPUT_PATH configuration variable and the OUTPUT_PATH variable must be set.

This is a filter and is not available via the Text virtual object.

repeat

[% item.repeat(3) %] Repeat the item 3 times

[% item.repeat(3, ' | ') %] Repeat the item 3 times separated with ' | '

replace

[% item.replace("\s+", "&nbsp;") %] Globally replace all space with &nbsp;

[% item.replace("foo", "bar", 0) %] Replace only the first instance of foo with bar.

[% item.replace("(\w+)", "($1)") %] Surround all words with parenthesis.

In CGI::Ex::Template and TT3 you may also use normal regular expression notation.

[% item.replace(/(\w+)/, "($1)") %] Same as before.

search

[% item.search("(\w+)") %] Tests if the given pattern is in the string.

In CGI::Ex::Template and TT3 you may also use normal regular expression notation.

[% item.search(/(\w+)/, "($1)") %] Same as before.

sin

[% item.sin %] Returns the sine of the item.

size

[% item.size %] Always returns 1.

split

[% item.split %] Returns an arrayref from the item split on " "

[% item.split("\s+") %] Returns an arrayref from the item split on /\s+/

[% item.split("\s+", 3) %] Returns an arrayref from the item split on /\s+/ splitting until 3 elements are found.

In CGI::Ex::Template and TT3 you may also use normal regular expression notation.

[% item.split( /\s+/, 3 ) %] Same as before.

sprintf

[% item = "%d %d" %]
[% item.sprintf(7, 8) %]

Uses the pattern stored in self, and passes it to sprintf with the passed arguments. Opposite from the fmt vmethod.

sqrt

[% item.sqrt %]

Returns the square root of the number.

srand

Calls the perl srand function to set the interal random seed. This will affect future calls to the rand vmethod.

stderr

[% item.stderr %] Print the item to the current STDERR handle.

substr

[% item.substr(i) %] Returns a substring of item starting at i and going to the end of the string.

[% item.substr(i, n) %] Returns a substring of item starting at i and going n characters.

trim

[% item.trim %] Strips leading and trailing whitespace.

uc

Same as the upper command. Returns upper cased string.

ucfirst

[% item.ucfirst %] Lower-case the leading letter.

upper

[% item.upper %] Return a upper cased string.

uri

[% item.uri %] Perform a very basic URI encoding.

url

[% item.url %] Perform a URI encoding - but some characters such
               as : and / are left intact.

LIST VIRTUAL METHODS

The following methods can be called on an arrayref type data structures (scalar types will automatically promote to a single element list and call these methods if needed):

Additionally, list virtual methods can be accessed via the List Virtual Object.

fmt

[% mylist.fmt('%s', ', ') %]
[% mylist.fmt('%6s', ', ') %]
[% mylist.fmt('%*s', ', ', 6) %]

Passed a pattern and an string to join on. Returns a string of the values of the list formatted with the passed pattern and joined with the passed string. Default pattern is %s and the default join string is a space.

first

[% mylist.first(3) %]  Returns a list of the first 3 items in the list.

grep

[% mylist.grep("^\w+\.\w+$") %] Returns a list of all items matching the pattern.

hash

[% mylist.hash %] Returns a hashref with the array indexes as keys and the values as values.

join

[% mylist.join %] Joins on space.
[% mylist.join(", ") Joins on the passed argument.

last

[% mylist.last(3) %]  Returns a list of the last 3 items in the list.

list

[% mylist.list %] Returns a reference to the list.

max

[% mylist.max %] Returns the last item in the array.

merge

[% mylist.merge(list2) %] Returns a new list with all defined items from list2 added.

nsort

[% mylist.nsort %] Returns the numerically sorted items of the list.  If the items are
hashrefs, a key containing the field to sort on can be passed.

pop

[% mylist.pop %] Removes and returns the last element from the arrayref (the stash is modified).

push

[% mylist.push(23) %] Adds an element to the end of the arrayref (the stash is modified).

pick

[% mylist.pick %] Returns a random item from the list.
[% ['a' .. 'z'].pick %]

An additional numeric argument is how many items to return.

[% ['a' .. 'z'].pick(8).join('') %]

Note: This filter is not available as of TT2.15.

reverse

[% mylist.reverse %] Returns the list in reverse order.

shift

[% mylist.shift %] Removes and returns the first element of the arrayref (the stash is modified).

size

[% mylist.size %] Returns the number of elements in the array.

slice

[% mylist.slice(i, n) %] Returns a list from the arrayref beginning at index i and continuing for n items.

sort

[% mylist.sort %] Returns the alphabetically sorted items of the list.  If the items are
hashrefs, a key containing the field to sort on can be passed.

splice

[% mylist.splice(i, n) %] Removes items from array beginning at i and continuing for n items.

[% mylist.splice(i, n, list2) %] Same as before, but replaces removed items with the items
from list2.

unique

[% mylist.unique %] Return a list of the unique items in the array.

unshift

[% mylist.unshift(23) %] Adds an item to the beginning of the arrayref.

HASH VIRTUAL METHODS

The following methods can be called on hash type data structures:

Additionally, list virtual methods can be accessed via the Hash Virtual Object.

fmt

[% myhash.fmt('%s => %s', "\n") %]
[% myhash.fmt('%4s => %5s', "\n") %]
[% myhash.fmt('%*s => %*s', "\n", 4, 5) %]

Passed a pattern and an string to join on. Returns a string of the key/value pairs of the hash formatted with the passed pattern and joined with the passed string. Default pattern is "%s\t%s" and the default join string is a newline.

defined

[% myhash.defined('a') %]  Checks if a is defined in the hash.

delete

[% myhash.delete('a') %]  Deletes the item from the hash.

Unlink Perl the value is not returned. Multiple values may be passed and represent the keys to be deleted.

each

[% myhash.each.join(", ") %]  Turns the contents of the hash into a list - subject
to change as TT is changing the operations of each and list.

exists

[% myhash.exists('a') %]  Checks if a is in the hash.

hash

[% myhash.hash %]  Returns a reference to the hash.

import

[% myhash.import(hash2) %]  Overlays the keys of hash2 over the keys of myhash.

item

[% myhash.item(key) %] Returns the hashes value for that key.

items

[% myhash.items %] Returns a list of the key and values (flattened hash)

keys

[% myhash.keys.join(', ') %] Returns an arrayref of the keys of the hash.

list

[% myhash.list %] Returns an arrayref with the hash as a single value (subject to change).

pairs

[% myhash.pairs %] Returns an arrayref of hashrefs where each hash contains {key => $key, value => $value}
for each value of the hash.

nsort

[% myhash.nsort.join(", ") %] Returns a numerically sorted list of the keys.

size

[% myhash.size %] Returns the number of key/value pairs in the hash.

sort

[% myhash.sort.join(", ") Returns an alphabetically sorted list.

values

[% myhash.values.join(', ') %] Returns an arrayref of the values of the hash.

VIRTUAL OBJECTS

TT3 has a concept of Text, List, and Hash virtual objects which provide direct access to the scalar, list, and hash virtual methods. In the TT3 engine this will allow for more concise generated code. Because CET does not generated perl code to be executed later, CET provides for these virtual objects but does so as more of a namespace (using the methods does not provide a speed optimization in your template - just may help clarify things).

[% a = "foo"; a.length %] => 3

[% a = "foo"; Text.length(a) %] => 3

[% a = Text.new("foo"); a.length %] => 3


[% a = [1 .. 30]; a.size %] => 30

[% a = [1 .. 30]; List.size(a) %] => 30

[% a = List.new(1 .. 30); a.size %] => 30


[% a = {a => 1, b => 2}; a.size %] => 2

[% a = {a => 1, b => 2}; Hash.size(a) %] => 2

[% a = Hash.new({a => 1, b => 2}); a.size %] => 2

[% a = Hash.new(a => 1, b => 2); a.size %] => 2

[% a = Hash.new(a = 1, b = 2); a.size %] => 2

[% a = Hash.new('a', 1, 'b', 2); a.size %] => 2

One limitation is that if you pass a key named "Text", "List", or "Hash" in your variable stash - the corresponding virtual object will be hidden.

Additionally, you can use all of the Virtual object methods with the pipe operator.

[% {a => 1, b => 2}
   | Hash.keys
   | List.join(", ") %] => a, b

Again, there aren't any speed optimizations to using the virtual objects in CET, but it can help clarify the intent in some cases.

Note: these aren't really objects. All of the "virtual objects" are references to the $SCALAR_OPS, $LIST_OPS, and $HASH_OPS hashes found in the $VOBJS hash of CGI::Ex::Template.

DIRECTIVES (TT Style)

This section contains the alphabetical list of DIRECTIVES available in the TT language. DIRECTIVES are the "functions" and control structures of the Template Toolkit mini-language. For further discussion and examples beyond what is listed below, please refer to the TT directives documentation.

[% IF 1 %]One[% END %]
[% FOREACH a = [1 .. 3] %]
    a = [% a %]
[% END %]

[% SET a = 1 %][% SET a = 2 %][% GET a %]

Multiple directives can be inside the same set of '[%' and '%]' tags as long as they are separated by space or semi-colons (;). Any block directive that can also be used as a post-operative directive (such as IF, WHILE, FOREACH, UNLESS, FILTER, and WRAPPER) must be separated from preceding directives with a semi-colon if it is being used as a block directive. It is more safe to always use a semi-colon. Note: separating by space is only available in CET but is a planned TT3 feature.

[% SET a = 1 ; SET a = 2 ; GET a %]
[% SET a = 1
   SET a = 2
   GET a
 %]

[% GET 1
     IF 0   # is a post-operative
   GET 2 %] # prints 2

[% GET 1;
   IF 0     # it is block based
     GET 2
   END
 %]         # prints 1

The following is the list of directives.

BLOCK

Saves a block of text under a name for later use in PROCESS, INCLUDE, and WRAPPER directives. Blocks may be placed anywhere within the template being processed including after where they are used.

[% BLOCK foo %]Some text[% END %]
[% PROCESS foo %]

Would print

Some text

[% INCLUDE foo %]
[% BLOCK foo %]Some text[% END %]

Would print

Some text

Anonymous BLOCKS can be used for capturing.

[% a = BLOCK %]Some text[% END %][% a %]

Would print

Some text

Anonymous BLOCKS can be used with macros.

BREAK

Alias for LAST. Used for exiting FOREACH and WHILE loops.

CALL

Calls the variable (and any underlying coderefs) as in the GET method, but always returns an empty string.

CASE

Used with the SWITCH directive. See the "SWITCH" directive.

CATCH

Used with the TRY directive. See the "TRY" directive.

CLEAR

Clears any of the content currently generated in the innermost block or template. This can be useful when used in conjunction with the TRY statement to clear generated content if an error occurs later.

CONFIG

Allow for changing the value of some compile time and runtime configuration options.

[% CONFIG
    ANYCASE   => 1
    PRE_CHOMP => '-'
%]

The following compile time configuration options may be set:

ANYCASE
INTERPOLATE
PRE_CHOMP
POST_CHOMP
V1DOLLAR
V2PIPE
V2EQUALS

The following runtime configuration options may be set:

DUMP
VMETHOD_FUNCTIONS

If non-named parameters as passed, they will show the current configuration:

[% CONFIG ANYCASE, PRE_CHOMP %]

CONFIG ANYCASE = undef
CONFIG PRE_CHOMP = undef

DEBUG

Used to reset the DEBUG_FORMAT configuration variable, or to turn DEBUG statements on or off. This only has effect if the DEBUG_DIRS or DEBUG_ALL flags were passed to the DEBUG configuration variable.

[% DEBUG format '($file) (line $line) ($text)' %]
[% DEBUG on %]
[% DEBUG off %]

DEFAULT

Similar to SET, but only sets the value if a previous value was not defined or was zero length.

[% DEFAULT foo = 'bar' %][% foo %] => 'bar'

[% foo = 'baz' %][% DEFAULT foo = 'bar' %][% foo %] => 'baz'

DUMP

DUMP inserts a Data::Dumper printout of the variable or expression. If no argument is passed it will dump the entire contents of the current variable stash (with private keys removed).

The output also includes the current file and line number that the DUMP directive was called from.

See the DUMP configuration item for ways to customize and control the output available to the DUMP directive.

[% DUMP %] # dumps everything

[% DUMP 1 + 2 %]

ELSE

Used with the IF directive. See the "IF" directive.

ELSIF

Used with the IF directive. See the "IF" directive.

END

Used to end a block directive.

FILTER

Used to apply different treatments to blocks of text. It may operate as a BLOCK directive or as a post operative directive. CET supports all of the filters in Template::Filters. The lines between scalar virtual methods and filters is blurred (or non-existent) in CET. Anything that is a scalar virtual method may be used as a FILTER.

TODO - enumerate the at least 7 ways to pass and use filters.

'|'

Alias for the FILTER directive. Note that | is similar to the '.' in CGI::Ex::Template. Therefore a pipe cannot be used directly after a variable name in some situations (the pipe will act only on that variable). This is the behavior employed by TT3. To get the TT2 behavior for a PIPE, use the V2PIPE configuration item.

FINAL

Used with the TRY directive. See the "TRY" directive.

FOR

Alias for FOREACH

FOREACH

Allows for iterating over the contents of any arrayref. If the variable is not an arrayref, it is automatically promoted to one.

[% FOREACH i IN [1 .. 3] %]
    The variable i = [% i %]
[%~ END %]

[% a = [1 .. 3] %]
[% FOREACH j IN a %]
    The variable j = [% j %]
[%~ END %]

Would print:

The variable i = 1
The variable i = 2
The variable i = 3

The variable j = 1
The variable j = 2
The variable j = 3

You can also use the "=" instead of "IN" or "in".

[% FOREACH i = [1 .. 3] %]
    The variable i = [% i %]
[%~ END %]

Same as before.

Setting into a variable is optional.

[% a = [1 .. 3] %]
[% FOREACH a %] Hi [% END %]

Would print:

hi  hi  hi

If the item being iterated is a hashref and the FOREACH does not set into a variable, then values of the hashref are copied into the variable stash.

[% FOREACH [{a => 1}, {a => 2}] %]
    Key a = [% a %]
[%~ END %]

Would print:

Key a = 1
Key a = 2

The FOREACH process uses the CGI::Ex::Template::Iterator class to handle iterations (It is compatible with Template::Iterator). During the FOREACH loop an object blessed into the iterator class is stored in the variable "loop".

The loop variable provides the following information during a FOREACH:

index  - the current index
max    - the max index of the list
size   - the number of items in the list
count  - index + 1
number - index + 1
first  - true if on the first item
last   - true if on the last item
next   - return the next item in the list
prev   - return the previous item in the list

The following:

[% FOREACH [1 .. 3] %] [% loop.count %]/[% loop.size %] [% END %]

Would print:

1/3  2/3  3/3

The iterator is also available using a plugin. This allows for access to multiple "loop" variables in a nested FOREACH directive.

[%~ USE outer_loop = Iterator(["a", "b"]) %]
[%~ FOREACH i = outer_loop %]
    [%~ FOREACH j = ["X", "Y"] %]
       [% outer_loop.count %]-[% loop.count %] = ([% i %] and [% j %])
    [%~ END %]
[%~ END %]

Would print:

1-1 = (a and X)
1-2 = (a and Y)
2-1 = (b and X)
2-2 = (b and Y)

FOREACH may also be used as a post operative directive.

[% "$i" FOREACH i = [1 .. 5] %] => 12345

GET

Return the value of a variable or expression.

[% GET a %]

The GET keyword may be omitted.

[% a %]

[% 7 + 2 - 3 %] => 6

See the section on VARIABLES.

IF (IF / ELSIF / ELSE)

Allows for conditional testing. Expects an expression as its only argument. If the expression is true, the contents of its block are processed. If false, the processor looks for an ELSIF block. If an ELSIF's expression is true then it is processed. Finally it looks for an ELSE block which is processed if none of the IF or ELSIF's expressions were true.

[% IF a == b %]A equaled B[% END %]

[% IF a == b -%]
    A equaled B
[%- ELSIF a == c -%]
    A equaled C
[%- ELSE -%]
    Couldn't determine that A equaled anything.
[%- END %]

IF may also be used as a post operative directive.

[% 'A equaled B' IF a == b %]

Note: If you are using HTML::Template style documents, the TMPL_IF tag parses using the limited HTML::Template parsing rules. However, you may use EXPR="" to embed a TT3 style expression.

INCLUDE

Parse the contents of a file or block and insert them. Variables defined or modifications made to existing variables are discarded after a template is included.

[% INCLUDE path/to/template.html %]

[% INCLUDE "path/to/template.html" %]

[% file = "path/to/template.html" %]
[% INCLUDE $file %]

[% BLOCK foo %]This is foo[% END %]
[% INCLUDE foo %]

Arguments may also be passed to the template:

[% INCLUDE "path/to/template.html" a = "An arg" b = "Another arg" %]

Filenames must be relative to INCLUDE_PATH unless the ABSOLUTE or RELATIVE configuration items are set.

Multiple filenames can be passed by separating them with a plus, a space, or commas (TT2 doesn't support the comma). Any supplied arguments will be used on all templates.

[% INCLUDE "path/to/template.html",
           "path/to/template2.html" a = "An arg" b = "Another arg" %]

INSERT

Insert the contents of a file without template parsing.

Filenames must be relative to INCLUDE_PATH unless the ABSOLUTE or RELATIVE configuration items are set.

Multiple filenames can be passed by separating them with a plus, a space, or commas (TT2 doesn't support the comma).

[% INSERT "path/to/template.html",
          "path/to/template2.html" %]

LAST

Used to exit out of a WHILE or FOREACH loop.

LOOP

This directive operates similar to the HTML::Template loop directive. The LOOP directive expects a single variable name. This variable name should point to an arrayref of hashrefs. The keys of each hashref will be added to the variable stash when it is iterated.

[% var a = [{b => 1}, {b => 2}, {b => 3}] %]

[% LOOP a %] ([% b %]) [% END %]

Would print:

(1)  (2)  (3)

If CET is in HT mode and GLOBAL_VARS is false, the contents of the hashref will be the only items available during the loop iteration.

If LOOP_CONTEXT_VARS is true, and $QR_PRIVATE is false (default when called through the output method), then the variables __first__, __last__, __inner__, __odd__, and __counter__ will be set. See the HTML::Template loop_context_vars configuration item for more information.

MACRO

Takes a directive and turns it into a variable that can take arguments.

[% MACRO foo(i, j) BLOCK %]You passed me [% i %] and [% j %].[% END %]

[%~ foo("a", "b") %]
[% foo(1, 2) %]

Would print:

You passed me a and b.
You passed me 1 and 2.

Another example:

[% MACRO bar(max) FOREACH i = [1 .. max] %]([% i %])[% END %]

[%~ bar(4) %]

Would print:

(1)(2)(3)(4)

META

Used to define variables that will be available via either the template or component namespace.

Once defined, they cannot be overwritten.

[% template.foobar %]
[%~ META foobar = 'baz' %]
[%~ META foobar = 'bing' %]

Would print:

baz

NEXT

Used to go to the next iteration of a WHILE or FOREACH loop.

PERL

Only available if the EVAL_PERL configuration item is true (default is false).

Allow eval'ing the block of text as perl. The block will be parsed and then eval'ed.

[% a = "BimBam" %]
[%~ PERL %]
    my $a = "[% a %]";
    print "The variable \$a was \"$a\"";
    $stash->set('b', "FooBar");
[% END %]
[% b %]

Would print:

The variable $a was "BimBam"
FooBar

During execution, anything printed to STDOUT will be inserted into the template. Also, the $stash and $context variables are set and are references to objects that mimic the interface provided by Template::Context and Template::Stash. These are provided for compatibility only. $self contains the current CGI::Ex::Template object.

PROCESS

Parse the contents of a file or block and insert them. Unlike INCLUDE, no variable localization happens so variables defined or modifications made to existing variables remain after the template is processed.

[% PROCESS path/to/template.html %]

[% PROCESS "path/to/template.html" %]

[% file = "path/to/template.html" %]
[% PROCESS $file %]

[% BLOCK foo %]This is foo[% END %]
[% PROCESS foo %]

Arguments may also be passed to the template:

[% PROCESS "path/to/template.html" a = "An arg" b = "Another arg" %]

Filenames must be relative to INCLUDE_PATH unless the ABSOLUTE or RELATIVE configuration items are set.

Multiple filenames can be passed by separating them with a plus, a space, or commas (TT2 doesn't support the comma). Any supplied arguments will be used on all templates.

[% PROCESS "path/to/template.html",
           "path/to/template2.html" a = "An arg" b = "Another arg" %]

RAWPERL

Only available if the EVAL_PERL configuration item is true (default is false). Similar to the PERL directive, but you will need to append to the $output variable rather than just calling PRINT.

RETURN

Used to exit the innermost block or template and continue processing in the surrounding block or template.

SET

Used to set variables.

[% SET a = 1 %][% a %]             => "1"
[% a = 1 %][% a %]                 => "1"
[% b = 1 %][% SET a = b %][% a %]  => "1"
[% a = 1 %][% SET a %][% a %]      => ""
[% SET a = [1, 2, 3] %][% a.1 %]   => "2"
[% SET a = {b => 'c'} %][% a.b %]  => "c"

STOP

Used to exit the entire process method (out of all blocks and templates). No content will be processed beyond this point.

SWITCH

Allow for SWITCH and CASE functionality.

[% a = "hi" %]
[% b = "bar" %]
[% SWITCH a %]
    [% CASE "foo"           %]a was foo
    [% CASE b               %]a was bar
    [% CASE ["hi", "hello"] %]You said hi or hello
    [% CASE DEFAULT         %]I don't know what you said
[% END %]

Would print:

You said hi or hello

TAGS

Change the type of enclosing braces used to delineate template tags. This remains in effect until the end of the enclosing block or template or until the next TAGS directive. Either a named set of tags must be supplied, or two tags themselves must be supplied.

[% TAGS html %]

[% TAGS <!-- --> %]

The named tags are (duplicated from TT):

asp       => ['<%',     '%>'    ], # ASP
default   => ['\[%',    '%\]'   ], # default
html      => ['<!--',   '-->'   ], # HTML comments
mason     => ['<%',     '>'     ], # HTML::Mason
metatext  => ['%%',     '%%'    ], # Text::MetaText
php       => ['<\?',    '\?>'   ], # PHP
star      => ['\[\*',   '\*\]'  ], # TT alternate
template  => ['\[%',    '%\]'   ], # Normal Template Toolkit
template1 => ['[\[%]%', '%[%\]]'], # allow TT1 style
tt2       => ['\[%',    '%\]'   ], # TT2

If custom tags are supplied, by default they are escaped using quotemeta. You may also pass explicitly quoted strings, or regular expressions as arguments as well (if your regex begins with a ', ", or / you must quote it.

[% TAGS [<] [>] %]          matches "[<] tag [>]"

[% TAGS '[<]' '[>]' %]      matches "[<] tag [>]"

[% TAGS "[<]" "[>]" %]      matches "[<] tag [>]"

[% TAGS /[<]/ /[>]/ %]      matches "< tag >"

[% TAGS ** ** %]            matches "** tag **"

[% TAGS /**/ /**/ %]        Throws an exception.

THROW

Allows for throwing an exception. If the exception is not caught via the TRY DIRECTIVE, the template will abort processing of the directive.

[% THROW mytypes.sometime 'Something happened' arg1 => val1 %]

See the TRY directive for examples of usage.

TRY

The TRY block directive will catch exceptions that are thrown while processing its block (It cannot catch parse errors unless they are in included files or evaltt'ed strings. The TRY block will then look for a CATCH block that will be processed. While it is being processed, the "error" variable will be set with the thrown exception as the value. After the TRY block - the FINAL block will be ran whether or not an error was thrown (unless a CATCH block throws an error).

Note: Parse errors cannot be caught unless they are in an eval FILTER, or are in a separate template being INCLUDEd or PROCESSed.

[% TRY %]
Nothing bad happened.
[% CATCH %]
Caught the error.
[% FINAL %]
This section runs no matter what happens.
[% END %]

Would print:

Nothing bad happened.
This section runs no matter what happens.

Another example:

[% TRY %]
[% THROW "Something happened" %]
[% CATCH %]
  Error:               [% error %]
  Error.type:          [% error.type %]
  Error.info:          [% error.info %]
[% FINAL %]
  This section runs no matter what happens.
[% END %]

Would print:

Error:               undef error - Something happened
Error.type:          undef
Error.info:          Something happened
This section runs no matter what happens.

You can give the error a type and more information including named arguments. This information replaces the "info" property of the exception.

[% TRY %]
[% THROW foo.bar "Something happened" "grrrr" foo => 'bar' %]
[% CATCH %]
  Error:               [% error %]
  Error.type:          [% error.type %]
  Error.info:          [% error.info %]
  Error.info.0:        [% error.info.0 %]
  Error.info.1:        [% error.info.1 %]
  Error.info.args.0:   [% error.info.args.0 %]
  Error.info.foo:      [% error.info.foo %]
[% END %]

Would print something like:

Error:               foo.bar error - HASH(0x82a395c)
Error.type:          foo.bar
Error.info:          HASH(0x82a395c)
Error.info.0:        Something happened
Error.info.1:        grrrr
Error.info.args.0:   Something happened
Error.info.foo:      bar

You can also give the CATCH block a type to catch. And you can nest TRY blocks. If types are specified, CET will try and find the closest matching type. Also, an error object can be re-thrown using $error as the argument to THROW.

[% TRY %]
  [% TRY %]
    [% THROW foo.bar "Something happened" %]
  [% CATCH bar %]
    Caught bar.
  [% CATCH DEFAULT %]
    Caught default - but rethrew.
    [% THROW $error %]
  [% END %]
[% CATCH foo %]
  Caught foo.
[% CATCH foo.bar %]
  Caught foo.bar.
[% CATCH %]
  Caught anything else.
[% END %]

Would print:

  Caught default - but rethrew.

Caught foo.bar.

UNLESS

Same as IF but condition is negated.

[% UNLESS 0 %]hi[% END %]  => hi

Can also be a post operative directive.

USE

Allows for loading a Template::Toolkit style plugin.

[% USE iter = Iterator(['foo', 'bar']) %]
[%~ iter.get_first %]
[% iter.size %]

Would print:

foo
2

Note that it is possible to send arguments to the new object constructor. It is also possible to omit the variable name being assigned. In that case the name of the plugin becomes the variable.

[% USE Iterator(['foo', 'bar', 'baz']) %]
[%~ Iterator.get_first %]
[% Iterator.size %]

Would print:

foo
3

Plugins that are loaded are looked up for in the namespace listed in the PLUGIN_BASE directive which defaults to Template::Plugin. So in the previous example, if Template::Toolkit was installed, the iter object would loaded by the class Template::Plugin::Iterator. In CET, an effective way to disable plugins is to set the PLUGIN_BASE to a non-existent base such as "_" (In TT it will still fall back to look in Template::Plugin).

Note: The iterator plugin will fall back and use CGI::Ex::Template::Iterator if Template::Toolkit is not installed. No other plugins come installed with CGI::Ex::Template.

The names of the Plugin being loaded from PLUGIN_BASE are case insensitive. However, using case insensitive names is bad as it requires scanning the @INC directories for any module matching the PLUGIN_BASE and caching the result (OK - not that bad).

If the plugin is not found and the LOAD_PERL directive is set, then CET will try and load a module by that name (note: this type of lookup is case sensitive and will not scan the @INC dirs for a matching file).

# The LOAD_PERL directive should be set to 1
[% USE cet = CGI::Ex::Template %]
[%~ cet.dump_parse_expr('2 * 3').replace('\s+', ' ') %]

Would print:

$VAR1 = [ [ undef, '*', '2', '3' ], 0 ];

See the PLUGIN_BASE, and PLUGINS configuration items.

See the documentation for Template::Manual::Plugins.

VIEW

Implement a TT style view. For more information, please see the Template::View documentation. This DIRECTIVE will correctly parse the arguments and then pass them along to a newly created Template::View object. It will fail if Template::View can not be found.

WHILE

Will process a block of code while a condition is true.

[% WHILE i < 3 %]
    [%~ i = i + 1 %]
    i = [% i %]
[%~ END %]

Would print:

i = 1
i = 2
i = 3

You could also do:

[% i = 4 %]
[% WHILE (i = i - 1) %]
    i = [% i %]
[%~ END %]

Would print:

i = 3
i = 2
i = 1

Note that (f = f - 1) is a valid expression that returns the value of the assignment. The parenthesis are not optional.

WHILE has a built in limit of 1000 iterations. This is controlled by the global variable $WHILE_MAX in CGI::Ex::Template.

WHILE may also be used as a post operative directive.

[% "$i" WHILE (i = i + 1) < 7 %] => 123456

WRAPPER

Block directive. Processes contents of its block and then passes them in the [% content %] variable to the block or filename listed in the WRAPPER tag.

[% WRAPPER foo b = 23 %]
My content to be processed ([% b %]).[% a = 2 %]
[% END %]

[% BLOCK foo %]
A header ([% a %]).
[% content %]
A footer ([% a %]).
[% END %]

This would print.

A header (2).
My content to be processed (23).
A footer (2).

The WRAPPER directive may also be used as a post operative directive.

[% BLOCK baz %]([% content %])[% END -%]
[% "foobar" WRAPPER baz %]

Would print

(foobar)');

Multiple filenames can be passed by separating them with a plus, a space, or commas (TT2 doesn't support the comma). Any supplied arguments will be used on all templates. Wrappers are processed in reverse order, so that the first wrapper listed will surround each subsequent wrapper listed. Variables from inner wrappers are available to the next wrapper that surrounds it.

[% WRAPPER "path/to/outer.html",
           "path/to/inner.html" a = "An arg" b = "Another arg" %]

DIRECTIVES (HTML::Template Style)

HTML::Template templates use directives that look similar to the following:

<TMPL_VAR NAME="foo">

<TMPL_IF NAME="bar">
  BAR
</TMPL_IF>

The normal set of HTML::Template directives are TMPL_VAR, TMPL_IF, TMPL_ELSE, TMPL_UNLESS, TMPL_INCLUDE, and TMPL_LOOP. These tags should have either a NAME attribute, an EXPR attribute, or a bare variable name that is used to specify the value to be operated. If a NAME is specified, it may only be a single level value (as opposed to a TT chained variable). In the case of the TMPL_INCLUDE directive, the NAME is the file to be included.

In CET, the EXPR attribute can be used with any of these types to specify TT compatible variable or expression that will be used for the value.

<TMPL_VAR NAME="foo">          Prints the value contained in foo
<TMPL_VAR foo>                 Prints the value contained in foo
<TMPL_VAR EXPR="foo">          Prints the value contained in foo

<TMPL_VAR NAME="foo.bar.baz">  Prints the value contained in {'foo.bar.baz'}
<TMPL_VAR EXPR="foo.bar.baz">  Prints the value contained in {foo}->{bar}->{baz}

<TMPL_IF foo>                  Prints FOO if foo is true
  FOO
</TMPL_IF

<TMPL_UNLESS foo>              Prints FOO unless foo is true
  FOO
</TMPL_UNLESS

<TMPL_INCLUDE NAME="foo.ht">   Includes the template in "foo.ht"

<TMPL_LOOP foo>                Iterates on the arrayref foo
  <TMPL_VAR name>
</TMPL_LOOP>

CGI::Ex::Template makes all of the other TT3 directives available in addition to the normal set of HTML::Template directives. For example, the following is valid in CET.

<TMPL_MACRO bar(n) BLOCK>You said <TMPL_VAR n></TMPL_MACRO>
<TMPL_GET bar("hello")>

The TMPL_VAR tag may also include an optional ESCAPE attribute. This specifies how the value of the tag should be escaped prior to substituting into the template.

Escape value |   Type of escape
---------------------------------
HTML, 1      |   HTML encoding
URL          |   URL encoding
JS           |   basic javascript encoding (\n, \r, and \")
NONE, 0      |   No encoding (default).

The TMPL_VAR tag may also include an optional DEFAULT attribute that contains a string that will be used if the variable returns false.

<TMPL_VAR foo DEFAULT="Foo was false">

OPERATORS

The following operators are available in CGI::Ex::Template. Except where noted these are the same operators available in TT. They are listed in the order of their precedence (the higher the precedence the tighter it binds).

.

The dot operator. Allows for accessing sub-members, methods, or virtual methods of nested data structures.

my $obj->process(\$content, {a => {b => [0, {c => [34, 57]}]}}, \$output);

[% a.b.1.c.0 %] => 34

Note: on access to hashrefs, any hash keys that match the sub key name will be used before a virtual method of the same name. For example if a passed hash contained pair with a keyname "defined" and a value of "2", then any calls to hash.defined(another_keyname) would always return 2 rather than using the vmethod named "defined." To get around this limitation use the "|" operator (listed next). Also - on objects the "." will always try and call the method by that name. To always call the vmethod - use "|".

|

The pipe operator. Similar to the dot operator. Allows for explicit calling of virtual methods and filters (filters are "merged" with virtual methods in CGI::Ex::Template and TT3) when accessing hashrefs and objects. See the note for the "." operator.

The pipe character is similar to TT2 in that it can be used in place of a directive as an alias for FILTER. It similar to TT3 in that it can be used for virtual method access. This duality is one source of difference between CGI::Ex::Template and TT2 compatibility. Templates that have directives that end with a variable name that then use the "|" directive to apply a filter will be broken as the "|" will be applied to the variable name.

The following two cases will do the same thing.

[% foo | html %]

[% foo FILTER html %]

Though they do the same thing, internally, foo|html is stored as a single variable while "foo FILTER html" is stored as the variable foo which is then passed to the FILTER html.

A TT2 sample that would break in CGI::Ex::Template or TT3 is:

[% PROCESS foo a = b | html %]

Under TT2 the content returned by "PROCESS foo a = b" would all be passed to the html filter. Under CGI::Ex::Template and TT3, b would be passed to the html filter before assigning it to the variable "a" before the template foo was processed.

A simple fix is to do any of the following:

[% PROCESS foo a = b FILTER html %]

[% | html %][% PROCESS foo a = b %][% END %]

[% FILTER html %][% PROCESS foo a = b %][% END %]

This shouldn't be too much hardship and offers the great return of disambiguating virtual method access.

\

Unary. The reference operator. Not well publicized in TT. Stores a reference to a variable for use later. Can also be used to "alias" long names.

[% f = 7 ; foo = \f ; f = 8 ; foo %] => 8

[% foo = \f.g.h.i.j.k; f.g.h.i.j.k = 7; foo %] => 7

[% f = "abcd"; foo = \f.replace("ab", "-AB-") ; foo %] => -AB-cd

[% f = "abcd"; foo = \f.replace("bc") ; foo("-BC-") %] => a-BC-d

[% f = "abcd"; foo = \f.replace ; foo("cd", "-CD-") %] => ab-CD-

++ --

Pre and post increment and decrement. My be used as either a prefix or postfix operator.

[% ++a %][% ++a %] => 12

[% a++ %][% a++ %] => 01

[% --a %][% --a %] => -1-2

[% a-- %][% a-- %] => 0-1

** ^ pow

Right associative binary. X raised to the Y power. This isn't available in TT 2.15.

[% 2 ** 3 %] => 8

!

Prefix not. Negation of the value.

-

Prefix minus. Returns the value multiplied by -1.

[% a = 1 ; b = -a ; b %] => -1

*

Left associative binary. Multiplication.

/ div DIV

Left associative binary. Division. Note that / is floating point division, but div and DIV are integer division.

[% 10  /  4 %] => 2.5
[% 10 div 4 %] => 2

% mod MOD

Left associative binary. Modulus.

[% 15 % 8 %] => 7

+

Left associative binary. Addition.

-

Left associative binary. Minus.

_ ~

Left associative binary. String concatenation.

[% "a" ~ "b" %] => ab

< > <= >=

Non associative binary. Numerical comparators.

lt gt le ge

Non associative binary. String comparators.

eq

Non associative binary. String equality test.

==

Non associative binary. In TT syntaxes the V2EQUALS configuration item defaults to true which means this operator will operate the same as the "eq" operator. Setting V2EQUALS to 0 will change this operator to mean numeric equality. You could also use [% ! (a <=> b) %] but that is a bit messy.

The HTML::Template syntaxes default V2EQUALS to 0 which means that it will test for numeric equality just as you would normally expect.

In either case - you should always use "eq" when you mean "eq". The V2EQUALS will most likely eventually default to 0.

ne

Non associative binary. String non-equality test.

!=

Non associative binary. In TT syntaxes the V2EQUALS configuration item defaults to true which means this operator will operate the same as the "ne" operator. Setting V2EQUALS to 0 will change this operator to mean numeric non-equality. You could also use [% (a <=> b) %] but that is a bit messy.

The HTML::Template syntaxes default V2EQUALS to 0 which means that it will test for numeric non-equality just as you would normally expect.

In either case - you should always use "ne" when you mean "ne". The V2EQUALS will most likely eventually default to 0.

<=>

Non associative binary. Numeric comparison operator. Returns -1 if the first argument is less than the second, 0 if they are equal, and 1 if the first argument is greater.

cmp

Non associative binary. String comparison operator. Returns -1 if the first argument is less than the second, 0 if they are equal, and 1 if the first argument is greater.

&&

Left associative binary. And. All values must be true. If all values are true, the last value is returned as the truth value.

[% 2 && 3 && 4 %] => 4

||

Right associative binary. Or. The first true value is returned.

[% 0 || '' || 7 %] => 7

Note: perl is left associative on this operator - but it doesn't matter because || has its own precedence level. Setting it to right allows for CET to short circuit earlier in the expression optree (left is (((1,2), 3), 4) while right is (1, (2, (3, 4))).

..

Non associative binary. Range creator. Returns an arrayref containing the values between and including the first and last arguments.

[% t = [1 .. 5] %] => variable t contains an array with 1,2,3,4, and 5

It is possible to place multiple ranges in the same [] constructor. This is not available in TT.

[% t = [1..3, 6..8] %] => variable t contains an array with 1,2,3,6,7,8

The .. operator is the only operator that returns a list of items.

? :

Ternary - right associative. Can be nested with other ?: pairs.

[% 1 ? 2 : 3 %] => 2
[% 0 ? 2 : 3 %] => 3

*= += -= /= **= %= ~=

Self-modifying assignment - right associative. Sets the left hand side to the operation of the left hand side and right (clear as mud). In order to not conflict with SET, FOREACH and other operations, this operator is only available in parenthesis.

[% a = 2 %][%  a += 3  %] --- [% a %]    => --- 5   # is handled by SET
[% a = 2 %][% (a += 3) %] --- [% a %]    => 5 --- 5

=

Assignment - right associative. Sets the left-hand side to the value of the righthand side. In order to not conflict with SET, FOREACH and other operations, this operator is only available in parenthesis. Returns the value of the righthand side.

[%  a = 1  %] --- [% a %]    => --- 1   # is handled by SET
[% (a = 1) %] --- [% a %]    => 1 --- 1

not NOT

Prefix. Lower precedence version of the '!' operator.

and AND

Left associative. Lower precedence version of the '&&' operator.

or OR

Right associative. Lower precedence version of the '||' operator.

{}

This operator is not used in TT. It is used internally by CGI::Ex::Template to delay the creation of a hash until the execution of the compiled template.

[]

This operator is not used in TT. It is used internally by CGI::Ex::Template to delay the creation of an array until the execution of the compiled template.

qr

This operator is not used in TT. It is used internally by CGI::Ex::Template to store a regular expression and its options. It will return a compiled Regexp object when compiled.

CHOMPING

Chomping refers to the handling of whitespace immediately before and immediately after template tags. By default, nothing happens to this whitespace. Modifiers can be placed just inside the opening and just before the closing tags to control this behavior.

Additionally, the PRE_CHOMP and POST_CHOMP configuration variables can be set and will globally control all chomping behavior for tags that do not have their own chomp modifier. PRE_CHOMP and POST_CHOMP can be set to any of the following values:

none:      0   +   Template::Constants::CHOMP_NONE
one:       1   -   Template::Constants::CHOMP_ONE
collapse:  2   =   Template::Constants::CHOMP_COLLAPSE
greedy:    3   ~   Template::Constants::CHOMP_GREEDY

CHOMP_NONE

Don't do any chomping. The "+" sign is used to indicate CHOMP_NONE.

Hello.

[%+ "Hi." +%]

Howdy.

Would print:

Hello.

Hi.

Howdy.

CHOMP_ONE (formerly known as CHOMP_ALL)

Delete any whitespace up to the adjacent newline. The "-" is used to indicate CHOMP_ONE.

Hello.

[%- "Hi." -%]

Howdy.

Would print:

Hello.
Hi.
Howdy.

CHOMP_COLLAPSE

Collapse adjacent whitespace to a single space. The "=" is used to indicate CHOMP_COLLAPSE.

Hello.

[%= "Hi." =%]

Howdy.

Would print:

Hello. Hi. Howdy.

CHOMP_GREEDY

Remove all adjacent whitespace. The "~" is used to indicate CHOMP_GREEDY.

Hello.

[%~ "Hi." ~%]

Howdy.

Would print:

Hello.Hi.Howdy.

CONFIGURATION (TT STYLE)

The following TT2 configuration variables are supported (in alphabetical order). Note: for further discussion you can refer to the TT config documentation.

Items may be passed in upper or lower case.

These variables should be passed to the "new" constructor.

my $obj = CGI::Ex::Template->new(
    VARIABLES  => \%hash_of_variables,
    AUTO_RESET => 0,
    TRIM       => 1,
    POST_CHOMP => "=",
    PRE_CHOMP  => "-",
);

ABSOLUTE

Boolean. Default false. Are absolute paths allowed for included files.

ANYCASE

Allow directive matching to be case insensitive.

[% get 23 %] prints 23 with ANYCASE => 1

AUTO_RESET

Boolean. Default 1. Clear blocks that were set during the process method.

BLOCKS

A hashref of blocks that can be used by the process method.

BLOCKS => {
    block_1 => sub { ... }, # coderef that returns a block
    block_2 => 'A String',  # simple string
},

Note that a Template::Document cannot be supplied as a value (TT supports this). However, it is possible to supply a value that is equal to the hashref returned by the load_parsed_tree method.

CACHE_SIZE

Number of compiled templates to keep in memory. Default undef. Undefined means to allow all templates to cache. A value of 0 will force no caching. The cache mechanism will clear templates that have not been used recently.

COMPILE_DIR

Base directory to store compiled templates. Default undef. Compiled templates will only be stored if one of COMPILE_DIR and COMPILE_EXT is set.

COMPILE_EXT

Extension to add to stored compiled template filenames. Default undef.

CONSTANTS

Hashref. Used to define variables that will be "folded" into the compiled template. Variables defined here cannot be overridden.

CONSTANTS => {my_constant => 42},

A template containing:

[% constants.my_constant %]

Will have the value 42 compiled in.

Constants defined in this way can be chained as in [% constant.foo.bar.baz %].

CONSTANT_NAMESPACE

Allow for setting the top level of values passed in CONSTANTS. Default value is 'constants'.

DEBUG

Takes a list of constants |'ed together which enables different debugging modes. Alternately the lowercase names may be used (multiple values joined by a ",").

The only supported TT values are:
DEBUG_UNDEF (2)    - debug when an undefined value is used.
DEBUG_DIRS  (8)    - debug when a directive is used.
DEBUG_ALL   (2047) - turn on all debugging.

Either of the following would turn on undef and directive debugging:

DEBUG => 'undef, dirs',            # preferred
DEBUG => 2 | 8,
DEBUG => DEBUG_UNDEF | DEBUG_DIRS, # constants from Template::Constants

DEBUG_FORMAT

Change the format of messages inserted when DEBUG has DEBUG_DIRS set on. This essentially the same thing as setting the format using the DEBUG directive.

DEFAULT

The name of a default template file to use if the passed one is not found.

DELIMITER

String to use to split INCLUDE_PATH with. Default is :. It is more straight forward to just send INCLUDE_PATH an arrayref of paths.

DUMP

Configures the behavior of the DUMP tag. May be set to 0, a hashref, or another true value. Default is true.

If set to 0, all DUMP directives will do nothing. This is useful if you would like to turn off the DUMP directives under some environments.

IF set to a true value (or undefined) then DUMP directives will operate.

If set to a hashref, the values of the hash can be used to configure the operation of the DUMP directives. The following are the values that can be set in this hash.

EntireStash

Default 1. If set to 0, then the DUMP directive will not print the entire contents of the stash when a DUMP directive is called without arguments.

handler

Defaults to an internal coderef. If set to a coderef, the DUMP directive will pass the arguments to be dumped and expects a string with the dumped data. This gives complete control over the dump process.

Note 1: The default handler makes sure that values matching the private variable regex are not included. If you install your own handler, you will need to take care of these variables if you intend for them to not be shown.

Note 2: If you would like the name of the variable to be dumped, include the string '$VAR1' and the DUMP directive will interpolate the value. For example, to dump all output as YAML - you could do the following:

DUMP => {
   handler => sub {
       require YAML;
       return "\$VAR1 =\n".YAML::Dump(shift);
   },
}

header

Default 1. Controls whether a header is printed for each DUMP directive. The header contains the file and line number the DUMP directive was called from. If set to 0 the headers are disabled.

html

Defaults to 1 if $ENV{'REQUEST_METHOD'} is set - 0 otherwise. If set to 1, then the output of the DUMP directive is passed to the html filter and encased in "pre" tags. If set to 0 no html encoding takes place.

Sortkeys, Useqq, Ident, Pad, etc

Any of the Data::Dumper configuration items may be passed.

END_TAG

Set a string to use as the closing delimiter for TT. Default is "%]".

ERROR

Used as a fall back when the processing of a template fails. May either be a single filename that will be used in all cases, or may be a hashref of options where the keynames represent error types that will be handled by the filename in their value. A key named default will be used if no other matching keyname can be found. The selection process is similar to that of the TRY/CATCH/THROW directives (see those directives for more information).

my $t = CGI::Ex::Template->new({
    ERROR => 'general/catch_all_errors.html',
});

my $t = CGI::Ex::Template->new({
    ERROR => {
        default   => 'general/catch_all_errors.html',
        foo       => 'catch_all_general_foo_errors.html',
        'foo.bar' => 'catch_foo_bar_errors.html',
    },
});

Note that the ERROR handler will only be used for errors during the processing of the main document. It will not catch errors that occur in templates found in the PRE_PROCESS, POST_PROCESS, and WRAPPER configuration items.

ERRORS

Same as the ERROR configuration item. Both may be used interchangably.

EVAL_PERL

Boolean. Default false. If set to a true value, PERL and RAWPERL blocks will be allowed to run. This is a potential security hole, as arbitrary perl can be included in the template. If Template::Toolkit is installed, a true EVAL_PERL value also allows the perl and evalperl filters to be used.

FILTERS

Allow for passing in TT style filters.

my $filters = {
    filter1 =>  sub { my $str = shift; $s =~ s/./1/gs; $s },
    filter2 => [sub { my $str = shift; $s =~ s/./2/gs; $s }, 0],
    filter3 => [sub { my ($context, @args) = @_; return sub { my $s = shift; $s =~ s/./3/gs; $s } }, 1],
};

my $str = q{
    [% a = "Hello" %]
    1 ([% a | filter1 %])
    2 ([% a | filter2 %])
    3 ([% a | filter3 %])
};

my $obj = CGI::Ex::Template->new(FILTERS => $filters);
$obj->process(\$str) || die $obj->error;

Would print:

1 (11111)
2 (22222)
3 (33333)

Filters passed in as an arrayref should contain a coderef and a value indicating if they are dynamic or static (true meaning dynamic). The dynamic filters are passed the pseudo context object and any arguments and should return a coderef that will be called as the filter. The filter coderef is then passed the string.

INCLUDE_PATH

A string or an arrayref or coderef that returns an arrayref that contains directories to look for files included by processed templates.

INCLUDE_PATHS

Non-TT item. Same as INCLUDE_PATH but only takes an arrayref. If not specified then INCLUDE_PATH is turned into an arrayref and stored in INCLUDE_PATHS. Overrides INCLUDE_PATH.

INTERPOLATE

Boolean. Specifies whether variables in text portions of the template will be interpolated. For example, the $variable and ${var.value} would be substituted with the appropriate values from the variable cache (if INTERPOLATE is on).

[% IF 1 %]The variable $variable had a value ${var.value}[% END %]

LOAD_PERL

Indicates if the USE directive can fall back and try and load a perl module if the indicated module was not found in the PLUGIN_BASE path. See the USE directive.

MAX_EVAL_RECURSE (CET only)

Will use $CGI::Ex::Template::MAX_EVAL_RECURSE if not present. Default is 50. Prevents runaway on the following:

[% f = "[% f|eval %]" %][% f|eval %]

MAX_MACRO_RECURSE (CET only)

Will use $CGI::Ex::Template::MAX_MACRO_RECURSE if not present. Default is 50. Prevents runaway on the following:

[% MACRO f BLOCK %][% f %][% END %][% f %]

NAMESPACE

No Template::Namespace::Constants support. Hashref of hashrefs representing constants that will be folded into the template at compile time.

CGI::Ex::Template->new(NAMESPACE => {constants => {
     foo => 'bar',
}});

Is the same as

CGI::Ex::Template->new(CONSTANTS => {
     foo => 'bar',
});

Any number of hashes can be added to the NAMESPACE hash.

NEGATIVE_STAT_TTL (Not in TT)

Defaults to STAT_TTL which defaults to $STAT_TTL which defaults to 1.

Similar to STAT_TTL - but represents the time-to-live seconds until a document that was not found is checked again against the system for modifications. Setting this number higher will allow for fewer file system accesses. Setting it to a negative number will allow for the file system to be checked every hit.

OUTPUT

Alternate way of passing in the output location for processed templates. If process is not passed an output argument, it will look for this value.

See the process method for a listing of possible values.

OUTPUT_PATH

Base path for files written out via the process method or via the redirect and file filters. See the redirect virtual method and the process method for more information.

PLUGINS

A hashref of mappings of plugin modules.

PLUGINS => {
   Iterator => 'Template::Plugin::Iterator',
   DBI      => 'MyDBI',
},

See the USE directive for more information.

PLUGIN_BASE

Default value is Template::Plugin. The base module namespace that template plugins will be looked for. See the USE directive for more information. May be either a single namespace, or an arrayref of namespaces.

POST_CHOMP

Set the type of chomping at the ending of a tag. See the section on chomping for more information.

POST_PROCESS

A list of templates to be processed and appended to the content after the main template. During this processing the "template" namespace will contain the name of the main file being processed.

This is useful for adding a global footer to all templates.

PRE_CHOMP

Set the type of chomping at the beginning of a tag. See the section on chomping for more information.

PRE_DEFINE

Same as the VARIABLES configuration item.

PRE_PROCESS

A list of templates to be processed before and pre-pended to the content before the main template. During this processing the "template" namespace will contain the name of the main file being processed.

This is useful for adding a global header to all templates.

PROCESS

Specify a file to use as the template rather than the one passed in to the ->process method.

RECURSION

Boolean. Default false. Indicates that INCLUDED or PROCESSED files can refer to each other in a circular manner. Be careful about recursion.

RELATIVE

Boolean. Default false. If true, allows filenames to be specified that are relative to the currently running process.

SEMICOLONS

Boolean. Default fast. If true, then the syntax will require that semi-colons separate multiple directives in the same tag. This is useful for keeping the syntax a little more clean as well as trouble shooting some errors.

START_TAG

Set a string to use as the opening delimiter for TT. Default is "[%".

STAT_TTL

Defaults to $STAT_TTL which defaults to 1. Represents time-to-live seconds until a cached in memory document is compared to the file system for modifications. Setting this number higher will allow for fewer file system accesses. Setting it to a negative number will allow for the file system to be checked every hit.

SYNTAX (not in TT)

Defaults to "cet". Indicates the syntax that will be used for parsing included templates or eval'ed strings. You can use the CONFIG directive to change the SYNTAX on the fly (it will not affect the syntax of the document currently being parsed).

The syntax may be passed in upper or lower case.

The available choices are:

cet - CGI::Ex::Template style - the same as TT3
tt3 - Template::Toolkit ver3 - same as CET
tt2 - Template::Toolkit ver2 - almost the same as TT3
tt1 - Template::Toolkit ver1 - almost the same as TT2
ht  - HTML::Template - same as HTML::Template::Expr without EXPR
hte - HTML::Template::Expr

Passing in a different syntax allows for the process method to use a non-TT syntax and for the output method to use a non-HT syntax.

The following is a sample of HTML::Template interface usage parsing a Template::Toolkit style document.

my $obj = CGI::Ex::Template->new(filename => 'my/template.tt'
                                 syntax   => 'cet');
$obj->param(\%swap);
print $obj->output;

The following is a sample of Template::Toolkit interface usage parsing a HTML::Template::Expr style document.

my $obj = CGI::Ex::Template->new(SYNTAX => 'hte');
$obj->process('my/template.ht', \%swap);

You can use the define_syntax method to add another custom syntax to the list of available options.

TAG_STYLE

Allow for setting the type of tag delimiters to use for parsing the TT. See the TAGS directive for a listing of the available types.

TRIM

Remove leading and trailing whitespace from blocks and templates. This operation is performed after all enclosed template tags have been executed.

UNDEFINED_ANY

This is not a TT configuration option. This option expects to be a code ref that will be called if a variable is undefined during a call to play_expr. It is passed the variable identity array as a single argument. This is most similar to the "undefined" method of Template::Stash. It allows for the "auto-defining" of a variable for use in the template. It is suggested that UNDEFINED_GET be used instead as UNDEFINED_ANY is a little to general in defining variables.

You can also sub class the module and override the undefined_any method.

UNDEFINED_GET

This is not a TT configuration option. This option expects to be a code ref that will be called if a variable is undefined during a call to GET. It is passed the variable identity array as a single argument. This is more useful than UNDEFINED_ANY in that it is only called during a GET directive rather than in embedded expressions (such as [% a || b || c %]).

You can also sub class the module and override the undefined_get method.

V1DOLLAR

This allows for some compatibility with TT1 templates. The only real behavior change is that [% $foo %] becomes the same as [% foo %]. The following is a basic table of changes invoked by using V1DOLLAR.

With V1DOLLAR        Equivalent Without V1DOLLAR (Normal default)
"[% foo %]"          "[% foo %]"
"[% $foo %]"         "[% foo %]"
"[% ${foo} %]"       "[% ${foo} %]"
"[% foo.$bar %]"     "[% foo.bar %]"
"[% ${foo.bar} %]"   "[% ${foo.bar} %]"
"[% ${foo.$bar} %]"  "[% ${foo.bar} %]"
"Text: $foo"         "Text: $foo"
"Text: ${foo}"       "Text: ${foo}"
"Text: ${$foo}"      "Text: ${foo}"

V2EQUALS

Default 1 in TT syntaxes, defaults to 0 in HTML::Template syntaxes.

If set to 1 then "==" is an alias for "eq" and "!= is an alias for "ne".

[% CONFIG V2EQUALS => 1 %][% ('7' == '7.0') || 0 %]
[% CONFIG V2EQUALS => 0 %][% ('7' == '7.0') || 0 %]

Prints

0
1

V2PIPE

Restores the behavior of the pipe operator to be compatible with TT2.

With V2PIPE = 1

[%- BLOCK a %]b is [% b %]
[% END %]
[%- PROCESS a b => 237 | repeat(2) %]

# output of block "a" with b set to 237 is passed to the repeat(2) filter

b is 237
b is 237

With V2PIPE = 0 (default)

[%- BLOCK a %]b is [% b %]
[% END %]
[% PROCESS a b => 237 | repeat(2) %]

# b set to 237 repeated twice, and b passed to block "a"

b is 237237

VARIABLES

A hashref of variables to initialize the template stash with. These variables are available for use in any of the executed templates. See the section on VARIABLES for the types of information that can be passed in.

VMETHOD_FUNCTIONS

Defaults to 1. All scalar virtual methods are available as top level functions as well. This is not true of TT2. In CGI::Ex::Template the following are equivalent:

[% "abc".length %]
[% length("abc") %]

You may set VMETHOD_FUNCTIONS to 0 to disable this behavior.

WRAPPER

Operates similar to the WRAPPER directive. The option can be given a single filename, or an arrayref of filenames that will be used to wrap the processed content. If an arrayref is passed the filenames are processed in reverse order, so that the first filename specified will end up being on the outside (surrounding all other wrappers).

my $t = CGI::Ex::Template->new(
    WRAPPER => ['my/wrappers/outer.html', 'my/wrappers/inner.html'],
);

Content generated by the PRE_PROCESS and POST_PROCESS will come before and after (respectively) the content generated by the WRAPPER configuration item.

See the WRAPPER direcive for more examples of how wrappers are construted.

CONFIGURATION (HTML::Template STYLE)

The following HTML::Template and HTML::Template::Expr configuration variables are supported (in HTML::Template documentation order). Note: for further discussion you can refer to the HT documentation. Many of the variables mentioned in the TT CONFIGURATION section apply here as well. Unless noted, these items only apply when using the output method.

Items may be passed in upper or lower case.

These variables should be passed to the "new" constructor.

my $obj = CGI::Ex::Template->new(
    type   => 'filename',
    source => 'my/template.ht',
    die_on_bad_params => 1,
    loop_context_vars => 1,
    global_vars       => 1
    post_chomp => "=",
    pre_chomp  => "-",
);

type

Can be one of filename, filehandle, arrayref, or scalarref. Indicates what type of input is in the "source" configuration item.

source

Stores where to read the input file. The type is specified in the "type" configuration item.

filename

Indicates a filename to read the template from. Same as putting the filename in the "source" item and setting "type" to "filename".

Must be set to enable caching.

filehandle

Should contain an open filehandle to read the template from. Same as putting the filehandle in the "source" item and setting "type" to "filehandle".

Will not be cached.

arrayref

Should contain an arrayref whose values are the lines of the template. Same as putting the arrayref in the "source" item and setting "type" to "arrayref".

Will not be cached.

scalarref

Should contain an reference to a scalar that contains the template. Same as putting the scalar ref in the "source" item and setting "type" to "scalarref".

Will not be cached.

cache

If set to one, then CET will use a global, in-memory document cache to store compiled templates in between calls. This is generally only useful in a mod_perl environment. The document is checked for a different modification time at each request.

blind_cache

Same as with cache enabled, but will not check if the document has been modified.

file_cache

If set to 1, will cache the compiled document on the file system. If true, file_cache_dir must be set.

file_cache_dir

The directory where to store cached documents when file_cache is true. This is similar to the TT compile_dir option.

double_file_cache

Uses a combination of file_cache and cache.

path

Same as INCLUDE_PATH when using the process method.

associate

May be a single CGI object or an arrayref of objects. The params from these objects will be added to the params during the output call.

case_sensitive

Allow passed variables set through the param method, or the associate configuration to be used case sensitively. Default is off. It is highly suggested that this be set to 1.

loop_context_vars

Default false. When true, calls to the loop directive will create the following variables that give information about the current iteration of the loop:

__first__   - True on first iteration only
__last__    - True on last iteration only
__inner__   - True on any iteration that isn't first or last
__odd__     - True on odd iterations
__counter__ - The iteration count

These variables are also available to LOOPs run under TT syntax if loop_context_vars is set and if QR_PRIVATE is set to 0.

no_includes

Default false. If true, calls to INCLUDE, PROCESS, WRAPPER and INSERT will fail. This option is also available when using the process method.

global_vars.

Default true in HTE mode. Default false in HT. Allows top level variables to be used in LOOPs. When false, only variables defined in the current LOOP iteration hashref will be available.

default_escape

Controls the type of escape used on named variables in TMPL_VAR directives. Can be one of HTML, URL, or JS. The values of TMPL_VAR directives will be encoded with this type unless they specify their own type via an ESCAPE attribute.

UNSUPPORTED HT CONFIGURATION

die_on_bad_params: CET does not resolve variables until the template is output.
force_untaint
strict: CET is strict on parsing HT documents.
shared_cache, double_cache: CET doesn't have shared caching. Yet.
search_path_on_include: CET will check the full path array on each include.
debug items: The HTML::Template style options are included here, but you can use the TT style DEBUG and DUMP directives to do intropection.
max_includes: CET uses TT's recursion protection.
filter: CET doesn't offer these.

UNSUPPORTED TT2 CONFIGURATION

LOAD_TEMPLATES

CGI::Ex::Template has its own mechanism for loading and storing compiled templates. TT would use a Template::Provider that would return a Template::Document. The closest thing in CGI::Ex::Template is the load_parsed_template method. There is no immediate plan to support the TT behavior.

LOAD_PLUGINS

CGI::Ex::Template uses its own mechanism for loading plugins. TT would use a Template::Plugins object to load plugins requested via the USE directive. The functionality for doing this in CGI::Ex::Template is contained in the list_plugins method and the play_USE method. There is no immediate plan to support the TT behavior.

Full support is offered for the PLUGINS and LOAD_PERL configuration items.

Also note that CGI::Ex::Template only natively supports the Iterator plugin. Any of the other plugins requested will need to provided by installing Template::Toolkit or the appropriate plugin module.

LOAD_FILTERS

CGI::Ex::Template uses its own mechanism for loading filters. TT would use the Template::Filters object to load filters requested via the FILTER directive. The functionality for doing this in CGI::Ex::Template is contained in the list_filters method and the play_expr method.

Full support is offered for the FILTERS configuration item.

TOLERANT

This option is used by the LOAD_TEMPLATES and LOAD_PLUGINS options and is not applicable in CGI::Ex::Template.

SERVICE

CGI::Ex::Template has no concept of service (theoretically the CGI::Ex::Template is the "service").

CONTEXT

CGI::Ex::Template provides its own pseudo context object to plugins, filters, and perl blocks. The CGI::Ex::Template model doesn't really allow for a separate context. CGI::Ex::Template IS the context.

STASH

CGI::Ex::Template manages its own stash of variables. A pseudo stash object is available via the pseudo context object for use in plugins, filters, and perl blocks.

PARSER

CGI::Ex::Template has its own built in parser. The closest similarity is the parse_tree method. The output of parse_tree is an optree that is later run by execute_tree. CET provides a backend to the Template::Parser::CET module which can be used to replace the default parser when using the standard Template::Toolkit library.

GRAMMAR

CGI::Ex::Template maintains its own grammar. The grammar is defined in the parse_tree method and the callbacks listed in the global $DIRECTIVES hashref.

VARIABLE PARSE TREE

CGI::Ex::Template parses templates into an tree of operations (an AST or abstract syntax tree). Even variable access is parsed into a tree. This is done in a manner somewhat similar to the way that TT operates except that nested variables such as foo.bar|baz contain the '.' or '|' in between each name level. Operators are parsed and stored as part of the variable (it may be more appropriate to say we are parsing a term or an expression).

The following table shows a variable or expression and the corresponding parsed tree (this is what the parse_expr method would return).

one                [ 'one',  0 ]
one()              [ 'one',  [] ]
one.two            [ 'one',  0, '.', 'two',  0 ]
one|two            [ 'one',  0, '|', 'two',  0 ]
one.$two           [ 'one',  0, '.', ['two', 0 ], 0 ]
one(two)           [ 'one',  [ ['two', 0] ] ]
one.${two().three} [ 'one',  0, '.', ['two', [], '.', 'three', 0], 0]
2.34               2.34
"one"              "one"
1 + 2              [ [ undef, '+', 1, 2 ], 0]
a + b              [ [ undef, '+', ['a', 0], ['b', 0] ], 0 ]
"one"|length       [ [ undef, '~', "one" ], 0, '|', 'length', 0 ]
"one $a two"       [ [ undef, '~', 'one ', ['a', 0], ' two' ], 0 ]
[0, 1, 2]          [ [ undef, '[]', 0, 1, 2 ], 0 ]
[0, 1, 2].size     [ [ undef, '[]', 0, 1, 2 ], 0, '.', 'size', 0 ]
['a', a, $a ]      [ [ undef, '[]', 'a', ['a', 0], [['a', 0], 0] ], 0]
{a  => 'b'}        [ [ undef, '{}', 'a', 'b' ], 0 ]
{a  => 'b'}.size   [ [ undef, '{}', 'a', 'b' ], 0, '.', 'size', 0 ]
{$a => b}          [ [ undef, '{}', ['a', 0], ['b', 0] ], 0 ]
a * (b + c)        [ [ undef, '*', ['a', 0], [ [undef, '+', ['b', 0], ['c', 0]], 0 ]], 0 ]
(a + b)            [ [ undef, '+', ['a', 0], ['b', 0] ]], 0 ]
(a + b) * c        [ [ undef, '*', [ [undef, '+', ['a', 0], ['b', 0] ], 0 ], ['c', 0] ], 0 ]
a ? b : c          [ [ undef, '?', ['a', 0], ['b', 0], ['c', 0] ], 0 ]
a || b || c        [ [ undef, '||', ['a', 0], [ [undef, '||', ['b', 0], ['c', 0] ], 0 ] ], 0 ]
! a                [ [ undef, '!', ['a', 0] ], 0 ]

Some notes on the parsing.

Operators are parsed as part of the variable and become part of the variable tree.

Operators are stored in the variable tree using an operator identity array which
contains undef as the first value, the operator, and the operator arguments.  This
allows for quickly descending the parsed variable tree and determining that the next
node is an operator.

Parenthesis () can be used at any point in an expression to disambiguate precedence.

"Variables" that appear to be literal strings or literal numbers
are returned as the literal (no operator tree).

The following perl can be typed at the command line to view the parsed variable tree:

perl -e 'use CGI::Ex::Template; print CGI::Ex::Template::dump_parse_expr("foo.bar + 2")."\n"'

Also the following can be included in a template to view the output in a template:

[% USE cet = CGI::Ex::Template %]
[%~ cet.dump_parse_expr('foo.bar + 2').replace('\s+', ' ') %]

SEMI PUBLIC METHODS

The following list of methods are other interesting methods of CET that may be re-implemented by subclasses of CET.

dump_parse

This method allows for returning a Data::Dumper dump of a parsed template. It is mainly used for testing.

dump_parse_expr

This method allows for returning a Data::Dumper dump of a parsed variable. It is mainly used for testing.

exception

Creates an exception object blessed into the package listed in $CGI::Ex::Template::PACKAGE_EXCEPTION.

execute_tree

Executes a parsed tree (returned from parse_tree)

play_expr

Play the parsed expression. Turns a variable identity array into the parsed variable. This method is also responsible for playing operators and running virtual methods and filters. The variable identity array may also contain literal values, or operator identity arrays.

include_filename

Takes a file path, and resolves it into the full filename using paths from INCLUDE_PATH or INCLUDE_PATHS.

_insert

Resolves the file passed, and then returns its contents.

list_filters

Dynamically loads the filters list from Template::Filters when a filter is used that is not natively implemented in CET.

list_plugins

Returns an arrayref of modules that are under a base Namespace.

my @modules = @{ $self->list_plugins({base => 'Template::Plugins'}) }:

load_parsed_tree

Given a filename or a string reference will return a parsed document hash that contains the parsed tree.

my $doc = $self->load_parsed_tree($file) || $self->throw('undef', "Zero length content");

parse_args

Allow for the multitudinous ways that TT parses arguments. This allows for positional as well as named arguments. Named arguments can be separated with a "=" or "=>", and positional arguments should be separated by " " or ",". This only returns an array of parsed variables. To get the actual values, you must call play_expr on each value.

parse_tree

Used by load_parsed_tree. This is the main grammar engine of the program. It uses method in the $DIRECTIVES hashref to parse different DIRECTIVE TYPES.

parse_expr

Used to parse a variable, an expression, a literal string, or a number. It returns a parsed variable tree. Samples of parsed variables can be found in the VARIABLE PARSE TREE section.

set_variable

Used to set a variable. Expects a variable identity array and the value to set. It will autovifiy as necessary.

throw

Creates an exception object from the arguments and dies.

undefined_any

Called during play_expr if a value is returned that is undefined. This could be used to magically create variables on the fly. This is similar to Template::Stash::undefined. It is suggested that undefined_get be used instead. Default behavior returns undef. You may also pass a coderef via the UNDEFINED_ANY configuration variable. Also, you can try using the DEBUG => 'undef', configuration option which will throw an error on undefined variables.

undefined_get

Called when a variable is undefined during a GET directive. This is useful to see if a value that is about to get inserted into the text is undefined. undefined_any is a little too general for most cases. Also, you may pass a coderef via the UNDEFINED_GET configuration variable.

OTHER UTILITY METHODS

The following is a brief list of other methods used by CET. Generally, these shouldn't be overwritten by subclasses.

apply_precedence: Allows for parsed operator array to be translated to a tree based upon operator precedence.
context: Used to create a "pseudo" context object that allows for portability of TT plugins, filters, and perl blocks that need a context object.
debug_node: Used to get debug info on a directive if DEBUG_DIRS is set.
filter_*: Methods by these names implement filters that are more complex than one liners.
get_line_number_by_index: Used to turn string index position into line number
interpolate_node: Used for parsing text nodes for dollar variables when interpolate is on.
parse_*: Methods by these names are used by parse_tree to parse the template. These are the grammar.
play_*: Methods by these names are used by execute_tree to execute the parsed tree.
play_operator: Used to execute any found operators. The single argument is an operator identy returned by the parse_expr method (if the expression contained an operator). Normally you would just call play_expr instead and it will call play_operator if the structure contains an operator.
_process: Called by process and the PROCESS, INCLUDE and other directives.
slurp: Reads contents of passed filename - throws file exception on error.
split_paths: Used to split INCLUDE_PATH or other directives if an arrayref is not passed.
_vars: Return a reference to the current stash of variables. This is currently only used by the pseudo context object and may disappear at some point.
vmethod_*: Methods by these names implement virtual methods that are more complex than oneliners.

AUTHOR

Paul Seamons <paul at seamons dot com>

LICENSE

This module may be distributed under the same terms as Perl itself.

3 POD Errors

The following errors were encountered while parsing the POD:

Around line 1217:: You forgot a '=back' before '=head1'
Around line 1667:: =back doesn't take any parameters, but you said =back 4
Around line 3111:: You forgot a '=back' before '=head1'

To install CGI::Ex, copy and paste the appropriate command in to your terminal.

cpanm

cpanm CGI::Ex

CPAN shell

perl -MCPAN -e shell
install CGI::Ex

For more information on module installation, please visit the detailed CPAN module installation guide.

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NAME

SYNOPSIS

DESCRIPTION

PUBLIC METHODS

TODO

HOW IS CGI::Ex::Template DIFFERENT from Template::Toolkit

HOW IS CGI::Ex::Template DIFFERENT from HTML::Template

VARIABLES

GETTING VARIABLES

SETTING VARIABLES.

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EXPRESSIONS

VIRTUAL METHODS

SCALAR VIRTUAL METHODS AND FILTERS

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VIRTUAL OBJECTS

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DIRECTIVES (HTML::Template Style)

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UNSUPPORTED HT CONFIGURATION

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