NAME

Template - Front-end module to the Template Toolkit


SYNOPSIS

  use Template;
  # some useful options (see below for full list)
  my $config = {
      INCLUDE_PATH => '/search/path',  # or list ref
      INTERPOLATE  => 1,               # expand "$var" in plain text
      POST_CHOMP   => 1,               # cleanup whitespace 
      PRE_PROCESS  => 'header',        # prefix each template
      EVAL_PERL    => 1,               # evaluate Perl code blocks
  };
  # create Template object
  my $template = Template->new($config);
  # define template variables for replacement
  my $vars = {
      var1  => $value,
      var2  => \%hash,
      var3  => \@list,
      var4  => \&code,
      var5  => $object,
  };
  # specify input filename, or file handle, text reference, etc.
  my $input = 'myfile.html';
  # process input template, substituting variables
  $template->process($input, $vars)
      || die $template->error();


DESCRIPTION

This documentation describes the Template module which is the direct Perl interface into the Template Toolkit. It covers the use of the module and gives a brief summary of configuration options and template directives. Please see the Template::Manual manpage for the complete reference manual which goes into much greater depth about the features and use of the Template Toolkit. The the Template::Tutorial manpage is also available as an introductory guide to using the Template Toolkit.


METHODS

new(\%config)

The new() constructor method (implemented by the Template::Base base class) instantiates a new Template object. A reference to a hash array of configuration items may be passed as a parameter.

    my $tt = Template->new({
        INCLUDE_PATH => '/usr/local/templates',
        EVAL_PERL    => 1,
    }) || die $Template::ERROR, "\n";

A reference to a new Template object is returned, or undef on error. In the latter case, the error message can be retrieved by calling error() as a class method (e.g. Template->error()) or by examining the $ERROR package variable directly (e.g. $Template::ERROR).

    my $tt = Template->new(\%config)
        || die Template->error(), "\n";
    my $tt = Template->new(\%config)
        || die $Template::ERROR, "\n";

For convenience, configuration items may also be specified as a list of items instead of a hash array reference. These are automatically folded into a hash array by the constructor.

    my $tt = Template->new(INCLUDE_PATH => '/tmp', POST_CHOMP => 1)
        || die $Template::ERROR, "\n";

process($template, \%vars, $output)

The process() method is called to process a template. The first parameter indicates the input template as one of: a filename relative to INCLUDE_PATH, if defined; a reference to a text string containing the template text; or a file handle reference (e.g. IO::Handle or sub-class) or GLOB (e.g. \*STDIN), from which the template can be read. A reference to a hash array may be passed as the second parameter, containing definitions of template variables.

    $text = "[% INCLUDE header %]\nHello world!\n[% INCLUDE footer %]";
    # filename
    $tt->process('welcome.tt2')
        || die $tt->error(), "\n";
    # text reference
    $tt->process(\$text)
        || die $tt->error(), "\n";
    # GLOB
    $tt->process(\*DATA)
        || die $tt->error(), "\n";
    __END__
    [% INCLUDE header %]
    This is a template defined in the __END__ section which is 
    accessible via the DATA "file handle".
    [% INCLUDE footer %]

By default, the processed template output is printed to STDOUT. The process() method then returns 1 to indicate success. A third parameter may be passed to the process() method to specify a different output location. This value may be one of: a plain string indicating a filename which will be opened (relative to OUTPUT_PATH, if defined) and the output written to; a file GLOB opened ready for output; a reference to a scalar (e.g. a text string) to which output/error is appended; a reference to a subroutine which is called, passing the output as a parameter; or any object reference which implements a 'print' method (e.g. IO::Handle, Apache::Request, etc.) which will be called, passing the generated output as a parameter.

Examples:

    # output filename
    $tt->process('welcome.tt2', $vars, 'welcome.html')
        || die $tt->error(), "\n";
    # reference to output subroutine
    sub myout {
        my $output = shift;
        ...
    }
    $tt->process('welcome.tt2', $vars, \&myout)
        || die $tt->error(), "\n";
    # reference to output text string
    my $output = '';
    $tt->process('welcome.tt2', $vars, \$output)
        || die $tt->error(), "\n";
    
    print "output: $output\n";

In an Apache/mod_perl handler:

    sub handler {
        my $req = shift;
        ...
        # direct output to Apache::Request via $req->print($output)
        $tt->process($file, $vars, $req) || do {
            $req->log_reason($tt->error());
            return SERVER_ERROR;
        };
        return OK;
    }

The OUTPUT configuration item can be used to specify a default output location other than \*STDOUT. The OUTPUT_PATH specifies a directory which should be prefixed to all output locations specified as filenames.

    my $tt = Template->new({
        OUTPUT      => sub { ... },       # default
        OUTPUT_PATH => '/tmp',
        ...
    }) || die Template->error(), "\n";
    # use default OUTPUT (sub is called)
    $tt->process('welcome.tt2', $vars)
        || die $tt->error(), "\n";
    # write file to '/tmp/welcome.html'
    $tt->process('welcome.tt2', $vars, 'welcome.html')
        || die $tt->error(), "\n";

The process() method returns 1 on success or undef on error. The error message generated in the latter case can be retrieved by calling the error() method. See also CONFIGURATION SUMMARY which describes how error handling may be further customised.

error()

When called as a class method, it returns the value of the $ERROR package variable. Thus, the following are equivalent.

    my $tt = Template->new()
        || die Template->error(), "\n";
    my $tt = Template->new()
        || die $Template::ERROR, "\n";

When called as an object method, it returns the value of the internal _ERROR variable, as set by an error condition in a previous call to process().

    $tt->process('welcome.tt2')
        || die $tt->error(), "\n";

Errors are represented in the Template Toolkit by objects of the Template::Exception class. If the process() method returns a false value then the error() method can be called to return an object of this class. The type() and info() methods can called on the object to retrieve the error type and information string, respectively. The as_string() method can be called to return a string of the form ``$type - $info''. This method is also overloaded onto the stringification operator allowing the object reference itself to be printed to return the formatted error string.

    $tt->process('somefile') || do {
        my $error = $tt->error();
        print "error type: ", $error->type(), "\n";
        print "error info: ", $error->info(), "\n";
        print $error, "\n";
    };

service()

The Template module delegates most of the effort of processing templates to an underlying Template::Service object. This method returns a reference to that object.

context()

The Template::Service module uses a core Template::Context object for runtime processing of templates. This method returns a reference to that object and is equivalent to $template->service->context();


CONFIGURATION SUMMARY

The following list gives a short summary of each Template Toolkit configuration option. See the Template::Manual::Config manpage for full details.

Template Style and Parsing Options

START_TAG, END_TAG
Define tokens that indicate start and end of directives (default: '[%' and '%]').

TAG_STYLE
Set START_TAG and END_TAG according to a pre-defined style (default: 'template', as above).

PRE_CHOMP, POST_CHOMP
Remove whitespace before/after directives (default: 0/0).

TRIM
Remove leading and trailing whitespace from template output (default: 0).

INTERPOLATE
Interpolate variables embedded like $this or ${this} (default: 0).

ANYCASE
Allow directive keywords in lower case (default: 0 - UPPER only).

Template Files and Blocks

INCLUDE_PATH
One or more directories to search for templates.

DELIMITER
Delimiter for separating paths in INCLUDE_PATH (default: ':').

ABSOLUTE
Allow absolute file names, e.g. /foo/bar.html (default: 0).

RELATIVE
Allow relative filenames, e.g. ../foo/bar.html (default: 0).

DEFAULT
Default template to use when another not found.

BLOCKS
Hash array pre-defining template blocks.

AUTO_RESET
Enabled by default causing BLOCK definitions to be reset each time a template is processed. Disable to allow BLOCK definitions to persist.

RECURSION
Flag to permit recursion into templates (default: 0).

Template Variables

VARIABLES, PRE_DEFINE
Hash array of variables and values to pre-define in the stash.

Runtime Processing Options

EVAL_PERL
Flag to indicate if PERL/RAWPERL blocks should be processed (default: 0).

PRE_PROCESS, POST_PROCESS
Name of template(s) to process before/after main template.

PROCESS
Name of template(s) to process instead of main template.

ERROR
Name of error template or reference to hash array mapping error types to templates.

OUTPUT
Default output location or handler.

OUTPUT_PATH
Directory into which output files can be written.

DEBUG
Flag which, when enabled, causes any access to an undefined variable to be raised as an 'undef' error.

Caching and Compiling Options

CACHE_SIZE
Maximum number of compiled templates to cache in memory (default: undef - cache all)

COMPILE_EXT
Filename extension for compiled template files (default: undef - don't compile).

COMPILE_DIR
Root of directory in which compiled template files should be written (default: undef - don't compile).

Plugins and Filters

PLUGINS
Reference to a hash array mapping plugin names to Perl packages.

PLUGIN_BASE
One or more base classes under which plugins may be found.

LOAD_PERL
Flag to indicate regular Perl modules should be loaded if a named plugin can't be found (default: 0).

FILTERS
Hash array mapping filter names to filter subroutines or factories.

Compatibility, Customisation and Extension

V1DOLLAR
Backwards compatibility flag enabling version 1.* handling (i.e. ignore it) of leading '$' on variables (default: 0 - '$' indicates interpolation).

LOAD_TEMPLATES
List of template providers.

LOAD_PLUGINS
List of plugin providers.

LOAD_FILTERS
List of filter providers.

TOLERANT
Set providers to tolerate errors as declinations (default: 0).

SERVICE
Reference to a custom service object (default: Template::Service).

CONTEXT
Reference to a custom context object (default: Template::Context).

STASH
Reference to a custom stash object (default: Template::Stash).

PARSER
Reference to a custom parser object (default: Template::Parser).

GRAMMAR
Reference to a custom grammar object (default: Template::Grammar).


DIRECTIVE SUMMARY

The following list gives a short summary of each Template Toolkit directive. See the Template::Manual::Directives manpage for full details.

GET
Evaluate and print a variable or value.
    [%   GET variable %]    # 'GET' keyword is optional
    [%       variable %]
    [%       hash.key %]
    [%         list.n %]
    [%     code(args) %]
    [% obj.meth(args) %]
    [%  "value: $var" %]

CALL
As per GET but without printing result (e.g. call code)
    [%  CALL variable %]

SET
Assign a values to variables.
    [% SET variable = value %]    # 'SET' also optional
    [%     variable = other_variable
           variable = 'literal text @ $100'
           variable = "interpolated text: $var"
           list     = [ val, val, val, val, ... ]
           list     = [ val..val ]
           hash     = { var => val, var => val, ... }
    %]

DEFAULT
Like SET above, but variables are only set if currently unset (i.e. have no true value).
    [% DEFAULT variable = value %]

INSERT
Insert a file without any processing performed on the contents.
    [% INSERT legalese.txt %]

INCLUDE
Process another template file or block and include the output. Variables are localised.
    [% INCLUDE template %]
    [% INCLUDE template  var = val, ... %]

PROCESS
As INCLUDE above, but without localising variables.
    [% PROCESS template %]
    [% PROCESS template  var = val, ... %]

WRAPPER
Process the enclosed block WRAPPER ... END block then INCLUDE the named template, passing the block output in the 'content' variable.
    [% WRAPPER template %]
       content...
    [% END %]

BLOCK
Define a named template block for subsequent INCLUDE, PROCESS, etc.,
    [% BLOCK template %]
       content
    [% END %]

FOREACH
Repeat the enclosed FOREACH ... END block for each value in the list.
    [% FOREACH variable = [ val, val, val ] %]    # either
    [% FOREACH variable = list %]                 # or
    [% FOREACH list %]                            # or 
       content...
       [% variable %]
    [% END %]

WHILE
Enclosed WHILE ... END block is processed while condition is true.
    [% WHILE condition %]
       content
    [% END %]

IF / UNLESS / ELSIF / ELSE
Enclosed block is processed if the condition is true / false.
    [% IF condition %]
       content
    [% ELSIF condition %]
         content
    [% ELSE %]
         content
    [% END %]
    [% UNLESS condition %]
       content
    [% # ELSIF/ELSE as per IF, above %]
       content
    [% END %]

SWITCH / CASE
Multi-way switch/case statement.
    [% SWITCH variable %]
    [% CASE val1 %]
       content
    [% CASE [ val2, val3 ] %]
       content
    [% CASE %]         # or [% CASE DEFAULT %]
       content
    [% END %]

MACRO
Define a named macro.
    [% MACRO name <directive> %]
    [% MACRO name(arg1, arg2) <directive> %]
    ...
    [% name %]
    [% name(val1, val2) %]

FILTER
Process enclosed FILTER ... END block then pipe through a filter.
    [% FILTER name %]                       # either
    [% FILTER name( params ) %]             # or
    [% FILTER alias = name( params ) %]     # or
       content
    [% END %]

USE
Load a ``plugin'' module, or any regular Perl module if LOAD_PERL option is set.
    [% USE name %]                          # either
    [% USE name( params ) %]                # or
    [% USE var = name( params ) %]          # or
    ...
    [% name.method %]
    [% var.method %]

PERL / RAWPERL
Evaluate enclosed blocks as Perl code (requires EVAL_PERL option to be set).
    [% PERL %]
         # perl code goes here
         $stash->set('foo', 10);
         print "set 'foo' to ", $stash->get('foo'), "\n";
         print $context->include('footer', { var => $val });
    [% END %]
    [% RAWPERL %]
       # raw perl code goes here, no magic but fast.
       $output .= 'some output';
    [% END %]

TRY / THROW / CATCH / FINAL
Exception handling.
    [% TRY %]
         content
       [% THROW type info %]
    [% CATCH type %]
         catch content
       [% error.type %] [% error.info %]
    [% CATCH %] # or [% CATCH DEFAULT %]
         content
    [% FINAL %]
       this block is always processed
    [% END %]

NEXT
Jump straight to the next item in a FOREACH/WHILE loop.
    [% NEXT %]

LAST
Break out of FOREACH/WHILE loop.
    [% LAST %]

RETURN
Stop processing current template and return to including templates.
    [% RETURN %]

STOP
Stop processing all templates and return to caller.
    [% STOP %]

TAGS
Define new tag style or characters (default: [% %]).
    [% TAGS html %]
    [% TAGS <!-- --> %]

COMMENTS
Ignored and deleted.
    [% # this is a comment to the end of line
       foo = 'bar'
    %]
    [%# placing the '#' immediately inside the directive
        tag comments out the entire directive
    %]


AUTHOR

Andy Wardley <abw@andywardley.com>

http://www.andywardley.com/|http://www.andywardley.com/


VERSION

Template Toolkit version 2.08, released on 30 July 2002.


COPYRIGHT

  Copyright (C) 1996-2002 Andy Wardley.  All Rights Reserved.
  Copyright (C) 1998-2002 Canon Research Centre Europe Ltd.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself.