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.\"
.IX Title "Template::Document 3"
.TH Template::Document 3 2024-09-01 "perl v5.40.0" "User Contributed Perl Documentation"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH NAME
Template::Document \- Compiled template document object
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\&    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  => \*(AqAndy Wardley\*(Aq,
\&            version => 3.14,
\&        }
\&    }) || die $Template::Document::ERROR;
\&
\&    print $doc\->process($context);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This module defines an object class whose instances represent compiled
template documents.  The Template::Parser module creates a
\&\f(CW\*(C`Template::Document\*(C'\fR instance to encapsulate a template as it is compiled
into Perl code.
.PP
The constructor method, \fBnew()\fR, expects a reference to a hash array
containing the \f(CW\*(C`BLOCK\*(C'\fR, \f(CW\*(C`DEFBLOCKS\*(C'\fR and \f(CW\*(C`METADATA\*(C'\fR items.
.PP
The \f(CW\*(C`BLOCK\*(C'\fR 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 \f(CWeval()\fR.
.PP
The \f(CW\*(C`DEFBLOCKS\*(C'\fR item should reference a hash array containing further named
\&\f(CW\*(C`BLOCK\*(C'\fRs which may be defined in the template. The keys represent \f(CW\*(C`BLOCK\*(C'\fR
names and the values should be subroutine references or text strings of Perl
code as per the main \f(CW\*(C`BLOCK\*(C'\fR item.
.PP
The \f(CW\*(C`METADATA\*(C'\fR item should reference a hash array of metadata items relevant
to the document.
.PP
The \fBprocess()\fR method can then be called on the instantiated
\&\f(CW\*(C`Template::Document\*(C'\fR object, passing a reference to a Template::Context
object as the first parameter. This will install any locally defined blocks
(\f(CW\*(C`DEFBLOCKS\*(C'\fR) in the \f(CW\*(C`BLOCKS\*(C'\fR cache in the context (via a call to
\&\fBvisit()\fR) so that they may be subsequently
resolved by the context. The main \f(CW\*(C`BLOCK\*(C'\fR subroutine is then executed,
passing the context reference on as a parameter. The text returned from the
template subroutine is then returned by the \fBprocess()\fR method, after calling
the context \fBleave()\fR method to permit cleanup and
de-registration of named \f(CW\*(C`BLOCKS\*(C'\fR previously installed.
.PP
An \f(CW\*(C`AUTOLOAD\*(C'\fR method provides access to the \f(CW\*(C`METADATA\*(C'\fR items for the
document. The Template::Service module installs a reference to the main
\&\f(CW\*(C`Template::Document\*(C'\fR object in the stash as the \f(CW\*(C`template\*(C'\fR variable. This allows
metadata items to be accessed from within templates, including \f(CW\*(C`PRE_PROCESS\*(C'\fR
templates.
.PP
header:
.PP
.Vb 5
\&    <html>
\&    <head>
\&    <title>[% template.title %]
\&    </head>
\&    ...
.Ve
.PP
\&\f(CW\*(C`Template::Document\*(C'\fR objects are usually created by the Template::Parser
but can be manually instantiated or sub-classed to provide custom
template components.
.SH METHODS
.IX Header "METHODS"
.SS new(\e%config)
.IX Subsection "new(%config)"
Constructor method which accept a reference to a hash array containing the
structure as shown in this example:
.PP
.Vb 11
\&    $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  => \*(AqAndy Wardley\*(Aq,
\&            version => 3.14,
\&        }
\&    }) || die $Template::Document::ERROR;
.Ve
.PP
\&\f(CW\*(C`BLOCK\*(C'\fR and \f(CW\*(C`DEFBLOCKS\*(C'\fR items may be expressed as references to Perl subroutines
or as text strings containing Perl subroutine definitions, as is generated
by the Template::Parser module.  These are evaluated into subroutine references
using \f(CWeval()\fR.
.PP
Returns a new \f(CW\*(C`Template::Document\*(C'\fR object or \f(CW\*(C`undef\*(C'\fR on error. The
\&\fBerror()\fR class method can be called, or the \f(CW$ERROR\fR
package variable inspected to retrieve the relevant error message.
.SS process($context)
.IX Subsection "process($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
\&\fBvisit()\fR method, processes its own template,
(passing the context reference as a parameter) and then calls
\&\fBleave()\fR in the context to allow cleanup.
.PP
.Vb 1
\&    print $doc\->process($context);
.Ve
.PP
Returns a text string representing the generated output for the template.
Errors are thrown via \f(CWdie()\fR.
.SS \fBblock()\fP
.IX Subsection "block()"
Returns a reference to the main \f(CW\*(C`BLOCK\*(C'\fR subroutine.
.SS \fBblocks()\fP
.IX Subsection "blocks()"
Returns a reference to the hash array of named \f(CW\*(C`DEFBLOCKS\*(C'\fR subroutines.
.SS \fBvariables()\fP
.IX Subsection "variables()"
Returns a reference to a hash of variables used in the template.
This requires the TRACE_VARS
option to be enabled.
.SS \fBmeta()\fP
.IX Subsection "meta()"
Return a reference to a hash of any META items defined in the template.
.SS AUTOLOAD
.IX Subsection "AUTOLOAD"
An autoload method returns \f(CW\*(C`METADATA\*(C'\fR items.
.PP
.Vb 1
\&    print $doc\->author();
.Ve
.SH "CLASS METHODS"
.IX Header "CLASS METHODS"
These methods are used internally.
.SS as_perl($content)
.IX Subsection "as_perl($content)"
This method generate a Perl representation of the template.
.PP
.Vb 10
\&    my $perl = Template::Document\->as_perl({
\&        BLOCK     => $main_block,
\&        DEFBLOCKS => {
\&            foo   => $foo_block,
\&            bar   => $bar_block,
\&        },
\&        METADATA  => {
\&            name  => \*(Aqmy_template\*(Aq,
\&        }
\&    });
.Ve
.SS write_perl_file(\e%config)
.IX Subsection "write_perl_file(%config)"
This method is used to write compiled Perl templates to disk.  If the
\&\f(CW\*(C`COMPILE_EXT\*(C'\fR option (to indicate a file extension for saving compiled
templates) then the Template::Parser module calls this subroutine before
calling the \fBnew()\fR 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 \f(CWrequire()\fR the file and have Perl parse and compile it into a
\&\f(CW\*(C`Template::Document\*(C'\fR.  Thus we have persistence of compiled templates.
.SH "INTERNAL FUNCTIONS"
.IX Header "INTERNAL FUNCTIONS"
.SS \fBcatch_warnings()\fP
.IX Subsection "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).
.SS \fBis_utf8()\fP
.IX Subsection "is_utf8()"
This is mapped to \f(CW\*(C`utf8::is_utf8\*(C'\fR for versions of Perl that have it (> 5.008)
or to \f(CW\*(C`Encode::is_utf8\*(C'\fR for Perl 5.008.  Earlier versions of Perl are not
supported.
.SH AUTHOR
.IX Header "AUTHOR"
Andy Wardley <abw@wardley.org> <http://wardley.org/>
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright (C) 1996\-2013 Andy Wardley.  All Rights Reserved.
.PP
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Template, Template::Parser