Template::Document(3)

NAME
Template::Document - Compiled template document object

SYNOPSIS
    use Template::Document;

    $doc = Template::Document->new({
        BLOCK => sub { # some perl code; return $some_text },
        DEFBLOCKS => {
            header => sub { # more perl code; return $some_text },
            footer => sub { # blah blah blah; return $some_text },
        },
        METADATA => {
            author  => 'Andy Wardley',
            version => 3.14,
        }
    }) || die $Template::Document::ERROR;

    print $doc->process($context);

DESCRIPTION
This module defines an object class whose instances represent compiled template documents. The Template::Parser module creates a "Template::Document" instance to encapsulate a template as it is compiled into Perl code.

The constructor method, new(), expects a reference to a hash array containing the "BLOCK", "DEFBLOCKS" and "METADATA" items.

The "BLOCK" item should contain a reference to a Perl subroutine or a textual representation of Perl code, as generated by the Template::Parser module. This is then evaluated into a subroutine reference using "eval()".

The "DEFLOCKS" item should reference a hash array containing further named "BLOCK"s which may be defined in the template. The keys represent "BLOCK" names and the values should be subroutine references or text strings of Perl code as per the main "BLOCK" item.

The "METADATA" item should reference a hash array of metadata items relevant to the document.

The process() method can then be called on the instantiated "Template::Document" object, passing a reference to a Template::Context object as the first parameter. This will install any locally defined blocks ("DEFBLOCKS") in the "BLOCKS" cache in the context (via a call to visit()) so that they may be subsequently resolved by the context. The main "BLOCK" subroutine is then executed, passing the context reference on as a parameter. The text returned from the template subroutine is then returned by the process() method, after calling the context leave() method to permit cleanup and de-registration of named "BLOCKS" previously installed.

An "AUTOLOAD" method provides access to the "METADATA" items for the document. The Template::Service module installs a reference to the main "Template::Document" object in the stash as the "template" variable. This allows metadata items to be accessed from within templates, including "PRE_PROCESS" templates.

header:

    <html>
    <head>
    <title>[% template.title %]
    </head>
    ...

"Template::Document" objects are usually created by the Template::Parser but can be manually instantiated or sub-classed to provide custom template components.

METHODS

  new(\%config)
Constructor method which accept a reference to a hash array containing the structure as shown in this example:

    $doc = Template::Document->new({
        BLOCK => sub { # some perl code; return $some_text },
        DEFBLOCKS => {
            header => sub { # more perl code; return $some_text },
            footer => sub { # blah blah blah; return $some_text },
        },
        METADATA => {
            author  => 'Andy Wardley',
            version => 3.14,
        }
    }) || die $Template::Document::ERROR;

"BLOCK" and "DEFBLOCKS" items may be expressed as references to Perl subroutines or as text strings containing Perl subroutine definitions, as is generated by the Template::Parser module. These are evaluated into subroutine references using "eval()".

Returns a new "Template::Document" object or "undef" on error. The error() class method can be called, or the $ERROR package variable inspected to retrieve the relevant error message.

  process($context)
Main processing routine for the compiled template document. A reference to a Template::Context object should be passed as the first parameter. The method installs any locally defined blocks via a call to the context visit() method, processes its own template, (passing the context reference as a parameter) and then calls leave() in the context to allow cleanup.

    print $doc->process($context);

Returns a text string representing the generated output for the template. Errors are thrown via "die()".

  block()
Returns a reference to the main "BLOCK" subroutine.

  blocks()
Returns a reference to the hash array of named "DEFBLOCKS" subroutines.

  variables()
Returns a reference to a hash of variables used in the template. This requires the TRACE_VARS option to be enabled.

  AUTOLOAD
An autoload method returns "METADATA" items.

    print $doc->author();

CLASS METHODS
These methods are used internally.

  as_perl($content)
This method generate a Perl representation of the template.

    my $perl = Template::Document->as_perl({
        BLOCK     => $main_block,
        DEFBLOCKS => {
            foo   => $foo_block,
            bar   => $bar_block,
        },
        METADATA  => {
            name  => 'my_template',
        }
    });

  write_perl_file(\%config)
This method is used to write compiled Perl templates to disk. If the "COMPILE_EXT" option (to indicate a file extension for saving compiled templates) then the Template::Parser module calls this subroutine before calling the new() constructor. At this stage, the parser has a representation of the template as text strings containing Perl code. We can write that to a file, enclosed in a small wrapper which will allow us to subsequently "require()" the file and have Perl parse and compile it into a "Template::Document". Thus we have persistence of compiled templates.

INTERNAL FUNCTIONS

  catch_warnings()
This is a simple handler used to catch any errors that arise when the compiled Perl template is first evaluated (that is, evaluated by Perl to create a template subroutine at compile, rather than the template being processed at runtime).

  is_utf8()
This is mapped to "utf8::is_utf8" for versions of Perl that have it (> 5.008) or to "Encode::is_utf8" for Perl 5.008. Earlier versions of Perl are not supported.

AUTHOR
Andy Wardley <abw@wardley.org> <http://wardley.org/>

COPYRIGHT
Copyright (C) 1996-2013 Andy Wardley. All Rights Reserved.

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

SEE ALSO
Template, Template::Parser