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Context.pm
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Context.pm
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#============================================================= -*-Perl-*-
#
# Template::Context
#
# DESCRIPTION
# Module defining a context in which a template document is processed.
# This is the runtime processing interface through which templates
# can access the functionality of the Template Toolkit.
#
# AUTHOR
# Andy Wardley <abw@kfs.org>
#
# COPYRIGHT
# Copyright (C) 1996-2000 Andy Wardley. All Rights Reserved.
# Copyright (C) 1998-2000 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.
#
#----------------------------------------------------------------------------
#
# $Id$
#
#============================================================================
package Template::Context;
require 5.004;
use strict;
use vars qw( $VERSION $DEBUG $AUTOLOAD );
use base qw( Template::Base );
use Template::Base;
use Template::Config;
use Template::Constants;
use Template::Exception;
$VERSION = sprintf("%d.%02d", q$Revision$ =~ /(\d+)\.(\d+)/);
#========================================================================
# ----- PUBLIC METHODS -----
#========================================================================
#------------------------------------------------------------------------
# template($name)
#
# General purpose method to fetch a template and return it in compiled
# form. In the usual case, the $name parameter will be a simple string
# containing the name of a template (e.g. 'header'). It may also be
# a reference to Template::Document object (or sub-class) or a Perl
# sub-routine. These are considered to be compiled templates and are
# returned intact. Finally, it may be a reference to any other kind
# of valid input source accepted by Template::Provider (e.g. scalar
# ref, glob, IO handle, etc).
#
# Templates may be cached at one of 3 different levels. The internal
# BLOCKS member is a local cache which holds references to all
# template blocks used or imported via PROCESS since the context's
# reset() method was last called. This is checked first and if the
# template is not found, the method then walks down the BLOCKSTACK
# list. This contains references to the block definition tables in
# any enclosing Template::Documents that we're visiting (e.g. we've
# been called via an INCLUDE and we want to access a BLOCK defined in
# the template that INCLUDE'd us). If nothing is defined, then we
# iterate through the LOAD_TEMPLATES providers list as a 'chain of
# responsibility' (see Design Patterns) asking each object to fetch()
# the template if it can.
#
# Returns the compiled template. On error, undef is returned and
# the internal ERROR value (read via error()) is set to contain an
# error message of the form "$name: $error".
#------------------------------------------------------------------------
sub template {
my ($self, $name) = @_;
my ($prefix, $blocks, $defblocks, $provider, $template, $error);
my $providers;
# references to Template::Document (or sub-class) objects objects, or
# CODE references are assumed to be pre-compiled templates and are
# returned intact
return $name
if UNIVERSAL::isa($name, 'Template::Document')
|| ref($name) eq 'CODE';
unless (ref $name) {
# we first look in the BLOCKS hash for a BLOCK that may have
# been imported from a template (via PROCESS)
return $template
if ($template = $self->{ BLOCKS }->{ $name });
# then we iterate through the BLKSTACK list to see if any of the
# Template::Documents we're visiting define this BLOCK
foreach $blocks (@{ $self->{ BLKSTACK } }) {
return $template
if $blocks && ($template = $blocks->{ $name });
}
# now it's time to ask the providers, so we look to see if any
# prefix is specified to indicate the desired provider set.
$prefix = undef;
if ($^O =~ /win/i) {
$prefix = $1 # let C:/foo through
if $name =~ s/^(\w{2,})://o;
}
else {
$prefix = $1
if $name =~ s/^(\w+)://o;
}
if (defined $prefix) {
$providers = $self->{ PREFIX_MAP }->{ $prefix }
|| return $self->throw(Template::Constants::ERROR_FILE,
"no providers for template prefix '$prefix'");
# print STDERR "prefix identified: $prefix\n";
}
}
$providers = $self->{ PREFIX_MAP }->{ default }
|| $self->{ LOAD_TEMPLATES }
unless $providers;
# finally we try the regular template providers which will
# handle references to files, text, etc., as well as templates
# reference by name
foreach my $provider (@$providers) {
($template, $error) = $provider->fetch($name);
return $template unless $error;
# return $self->error($template)
if ($error == Template::Constants::STATUS_ERROR) {
$self->throw($template) if ref $template;
$self->throw(Template::Constants::ERROR_FILE, $template);
}
}
# return $self->error("$name: not found");
$self->throw(Template::Constants::ERROR_FILE, "$name: not found");
}
#------------------------------------------------------------------------
# plugin($name, \@args)
#
# Calls on each of the LOAD_PLUGINS providers in turn to fetch() (i.e. load
# and instantiate) a plugin of the specified name. Additional parameters
# passed are propagated to the new() constructor for the plugin.
# Returns a reference to a new plugin object or other reference. On
# error, undef is returned and the appropriate error message is set for
# subsequent retrieval via error().
#------------------------------------------------------------------------
sub plugin {
my ($self, $name, $args) = @_;
my ($provider, $plugin, $error);
# request the named plugin from each of the LOAD_PLUGINS providers in turn
foreach my $provider (@{ $self->{ LOAD_PLUGINS } }) {
($plugin, $error) = $provider->fetch($name, $args, $self);
return $plugin unless $error;
if ($error == Template::Constants::STATUS_ERROR) {
$self->throw($plugin) if ref $plugin;
$self->throw(Template::Constants::ERROR_PLUGIN, $plugin);
}
}
$self->throw(Template::Constants::ERROR_PLUGIN, "$name: plugin not found");
}
#------------------------------------------------------------------------
# filter($name, \@args, $alias)
#
# Similar to plugin() above, but querying the LOAD_FILTERS providers to
# return filter instances. An alias may be provided which is used to
# save the returned filter in a local cache.
#------------------------------------------------------------------------
sub filter {
my ($self, $name, $args, $alias) = @_;
my ($provider, $filter, $error);
# use any cached version of the filter if no params provided
return $filter
if ! $args && ! ref $name
&& ($filter = $self->{ FILTER_CACHE }->{ $name });
# request the named filter from each of the FILTERS providers in turn
foreach my $provider (@{ $self->{ LOAD_FILTERS } }) {
$filter = $name, last
if ref $name;
($filter, $error) = $provider->fetch($name, $args, $self);
last unless $error;
if ($error == Template::Constants::STATUS_ERROR) {
$self->throw($filter) if ref $filter;
$self->throw(Template::Constants::ERROR_FILTER, $filter);
}
# return $self->error($filter)
# if $error == &Template::Constants::STATUS_ERROR;
}
return $self->error("$name: filter not found")
unless $filter;
# alias defaults to name if undefined
$alias = $name
unless defined($alias) or ref($name) or $args;
# cache FILTER if alias is valid
$self->{ FILTER_CACHE }->{ $alias } = $filter
if $alias;
return $filter;
}
#------------------------------------------------------------------------
# view(\%coonfig)
#
# Create a new Template::View bound to this context.
#------------------------------------------------------------------------
sub view {
my $self = shift;
require Template::View;
return Template::View->new($self, @_)
|| $self->throw(&Template::Constants::ERROR_VIEW,
$Template::View::ERROR);
}
#------------------------------------------------------------------------
# process($template, \%params) [% PROCESS template var = val, ... %]
#
# Processes the template named or referenced by the first parameter.
# The optional second parameter may reference a hash array of variable
# definitions. These are set before the template is processed by calling
# update() on the stash. Note that the context is not localised and
# these, and any other variables set in the template will retain their
# new values after this method returns.
#
# Returns the output of processing the template. Errors are thrown
# as Template::Exception objects via die().
#------------------------------------------------------------------------
sub process {
my ($self, $template, $params) = @_;
my ($trim, $blocks) = @$self{ qw( TRIM BLOCKS ) };
my (@compiled, $name, $compiled);
my ($stash, $tblocks, $error, $tmpout);
my $output = '';
# my ($blocks, $output);
# my $name = $template;
$template = [ $template ] unless ref $template eq 'ARRAY';
# fetch compiled template for each name specified
foreach $name (@$template) {
push(@compiled, $self->template($name));
}
# update stash with any new parameters passed
$self->{ STASH }->update($params);
$stash = $self->{ STASH };
foreach $name (@$template) {
$compiled = shift @compiled;
my $element = ref $compiled eq 'CODE'
? { (name => (ref $name ? '' : $name), modtime => time()) }
: $compiled;
$stash->set('component', $element);
# merge any local blocks defined in the Template::Document into our
# local BLOCKS cache
@$blocks{ keys %$tblocks } = values %$tblocks
if UNIVERSAL::isa($compiled, 'Template::Document')
&& ($tblocks = $compiled->blocks());
if (ref $compiled eq 'CODE') {
$tmpout = &$compiled($self);
}
elsif (ref $compiled) {
$tmpout = $compiled->process($self);
}
else {
$self->throw('file',
"invalid template reference: $compiled");
}
if ($trim) {
for ($tmpout) {
s/^\s+//;
s/\s+$//;
}
}
$output .= $tmpout;
}
return $output;
}
#------------------------------------------------------------------------
# include($template, \%params) [% INCLUDE template var = val, ... %]
#
# Similar to process() above but processing the template in a local
# context. Any variables passed by reference to a hash as the second
# parameter will be set before the template is processed and then
# revert to their original values before the method returns. Similarly,
# any changes made to non-global variables within the template will
# persist only until the template is processed.
#
# Returns the output of processing the template. Errors are thrown
# as Template::Exception objects via die().
#------------------------------------------------------------------------
sub include {
my ($self, $template, $params) = @_;
my $trim = $self->{ TRIM };
my (@compiled, $name, $compiled);
my ($stash, $error, $tmpout);
my $output = '';
$template = [ $template ] unless ref $template eq 'ARRAY';
# fetch compiled template for each name specified
foreach $name (@$template) {
push(@compiled, $self->template($name));
}
# localise the variable stash with any parameters passed
$stash = $self->{ STASH } = $self->{ STASH }->clone($params);
eval {
foreach $name (@$template) {
$compiled = shift @compiled;
my $element = ref $compiled eq 'CODE'
? { (name => (ref $name ? '' : $name), modtime => time()) }
: $compiled;
$stash->set('component', $element);
if (ref $compiled eq 'CODE') {
$tmpout = &$compiled($self);
}
elsif (ref $compiled) {
$tmpout = $compiled->process($self);
}
else {
$self->throw('file',
"invalid template reference: $compiled");
}
if ($trim) {
for ($tmpout) {
s/^\s+//;
s/\s+$//;
}
}
$output .= $tmpout;
}
};
$error = $@;
# ensure stash is delocalised before dying
$self->{ STASH } = $self->{ STASH }->declone();
$self->throw(ref $error
? $error : (Template::Constants::ERROR_FILE, $error))
if $error;
return $output;
}
sub old_include {
my ($self, $template, $params) = @_;
my ($error, $blocks);
my $output = '';
my $name = $template;
# request compiled template from cache
$template = $self->template($template);
# || die Template::Exception->new(&Template::Constants::ERROR_FILE,
# $self->{ _ERROR } || "$template: not found" );
# localise the variable stash with any parameters passed
$params ||= { };
$params->{ component } = ref $template eq 'CODE'
? { ref $name ? () : (name => $name, modtime => time()) }
: $template;
$self->{ STASH } = $self->{ STASH }->clone($params);
eval {
if (ref $template eq 'CODE') {
$output = &$template($self);
}
elsif (ref $template) {
$output = $template->process($self);
}
else {
die "invalid template reference: $template\n";
}
};
$error = $@;
$self->{ STASH } = $self->{ STASH }->declone();
die $error if $error;
if ($self->{ TRIM }) {
for ($output) {
s/^\s+//;
s/\s+$//;
}
}
return $output;
}
#------------------------------------------------------------------------
# insert($file)
#
# Insert the contents of a file without parsing.
#------------------------------------------------------------------------
sub insert {
my ($self, $file) = @_;
my ($providers, $text, $error);
my $output = '';
my $files = ref $file eq 'ARRAY' ? $file : [ $file ];
FILE: foreach $file (@$files) {
if ($file =~ s/^(\w{2,})://o) {
$providers = $self->{ PREFIX_MAP }->{ $1 }
|| return $self->throw(Template::Constants::ERROR_FILE,
"no providers for file prefix '$1'");
}
else {
$providers = $self->{ LOAD_TEMPLATES };
}
foreach my $provider (@$providers) {
($text, $error) = $provider->load($file);
next FILE unless $error;
if ($error == Template::Constants::STATUS_ERROR) {
$self->throw($text) if ref $text;
$self->throw(Template::Constants::ERROR_FILE, $text);
}
}
$self->throw(Template::Constants::ERROR_FILE, "$file: not found");
}
continue {
$output .= $text;
}
return $output;
}
#------------------------------------------------------------------------
# throw($type, $info, \$output) [% THROW errtype "Error info" %]
#
# Throws a Template::Exception object by calling die(). This method
# may be passed a reference to an existing Template::Exception object;
# a single value containing an error message which is used to
# instantiate a Template::Exception of type 'undef'; or a pair of
# values representing the exception type and info from which a
# Template::Exception object is instantiated. e.g.
#
# $context->throw($exception);
# $context->throw("I'm sorry Dave, I can't do that");
# $context->throw('denied', "I'm sorry Dave, I can't do that");
#
# An optional third parameter can be supplied in the last case which
# is a reference to the current output buffer containing the results
# of processing the template up to the point at which the exception
# was thrown. The RETURN and STOP directives, for example, use this
# to propagate output back to the user, but it can safely be ignored
# in most cases.
#
# This method rides on a one-way ticket to die() oblivion. It does not
# return in any real sense of the word, but should get caught by a
# surrounding eval { } block (e.g. a BLOCK or TRY) and handled
# accordingly, or returned to the caller as an uncaught exception.
#------------------------------------------------------------------------
sub throw {
my ($self, $error, $info, $output) = @_;
local $" = ', ';
# die! die! die!
if (UNIVERSAL::isa($error, 'Template::Exception')) {
# print STDERR "throwing existing exception [@$error]\n";
die $error;
}
elsif (defined $info) {
# print STDERR "throwing new exception [$error] [$info]\n";
die Template::Exception->new($error, $info, $output);
}
else {
$error ||= '';
# print STDERR "throwing an undefined exception [$error]\n";
die Template::Exception->new('undef', $error, $output);
}
# not reached
}
#------------------------------------------------------------------------
# catch($error, \$output)
#
# Called by various directives after catching an error thrown via die()
# from within an eval { } block. The first parameter contains the errror
# which may be a sanitized reference to a Template::Exception object
# (such as that raised by the throw() method above, a plugin object,
# and so on) or an error message thrown via die from somewhere in user
# code. The latter are coerced into 'undef' Template::Exception objects.
# Like throw() above, a reference to a scalar may be passed as an
# additional parameter to represent the current output buffer
# localised within the eval block. As exceptions are thrown upwards
# and outwards from nested blocks, the catch() method reconstructs the
# correct output buffer from these fragments, storing it in the
# exception object for passing further onwards and upwards.
#
# Returns a reference to a Template::Exception object..
#------------------------------------------------------------------------
sub catch {
my ($self, $error, $output) = @_;
if (UNIVERSAL::isa($error, 'Template::Exception')) {
$error->text($output) if $output;
return $error;
}
else {
return Template::Exception->new('undef', $error, $output);
}
}
#------------------------------------------------------------------------
# localise(\%params)
# delocalise()
#
# The localise() method creates a local copy of the current stash,
# allowing the existing state of variables to be saved and later
# restored via delocalise().
#
# A reference to a hash array may be passed containing local variable
# definitions which should be added to the cloned namespace. These
# values persist until delocalisation.
#------------------------------------------------------------------------
sub localise {
my $self = shift;
$self->{ STASH } = $self->{ STASH }->clone(@_);
}
sub delocalise {
my $self = shift;
$self->{ STASH } = $self->{ STASH }->declone();
}
#------------------------------------------------------------------------
# visit($blocks)
#
# Each Template::Document calls the visit() method on the context
# before processing itself. It passes a reference to the hash array
# of named BLOCKs defined within the document, allowing them to be
# added to the internal BLKSTACK list which is subsequently used by
# template() to resolve templates.
# from a provider.
#------------------------------------------------------------------------
sub visit {
my ($self, $blocks) = @_;
unshift(@{ $self->{ BLKSTACK } }, $blocks)
}
#------------------------------------------------------------------------
# leave()
#
# The leave() method is called when the document has finished
# processing itself. This removes the entry from the BLKSTACK list
# that was added visit() above. For persistance of BLOCK definitions,
# the process() method (i.e. the PROCESS directive) does some extra
# magic to copy BLOCKs into a shared hash.
#------------------------------------------------------------------------
sub leave {
my $self = shift;
shift(@{ $self->{ BLKSTACK } });
}
#------------------------------------------------------------------------
# define_block($name, $block)
#
# Adds a new BLOCK definition to the local BLOCKS cache. $block may
# be specified as a reference to a sub-routine or Template::Document
# object or as text which is compiled into a template. Returns a true
# value (the $block reference or compiled block reference) if
# succesful or undef on failure. Call error() to retrieve the
# relevent error message (i.e. compilation failure).
#------------------------------------------------------------------------
sub define_block {
my ($self, $name, $block) = @_;
$block = $self->template(\$block)
|| return undef
unless ref $block;
$self->{ BLOCKS }->{ $name } = $block;
}
#------------------------------------------------------------------------
# define_filter($name, $filter, $is_dynamic)
#
# Adds a new FILTER definition to the local FILTER_CACHE.
#------------------------------------------------------------------------
sub define_filter {
my ($self, $name, $filter, $is_dynamic) = @_;
my ($result, $error);
$filter = [ $filter, 1 ] if $is_dynamic;
foreach my $provider (@{ $self->{ LOAD_FILTERS } }) {
($result, $error) = $provider->store($name, $filter);
return 1 unless $error;
$self->throw(&Template::Constants::ERROR_FILTER, $result)
if $error == &Template::Constants::STATUS_ERROR;
}
$self->throw(&Template::Constants::ERROR_FILTER,
"FILTER providers declined to store filter $name");
}
#------------------------------------------------------------------------
# reset()
#
# Reset the state of the internal BLOCKS hash to clear any BLOCK
# definitions imported via the PROCESS directive. Any original
# BLOCKS definitions passed to the constructor will be restored.
#------------------------------------------------------------------------
sub reset {
my ($self, $blocks) = @_;
$self->{ BLKSTACK } = [ ];
$self->{ BLOCKS } = { %{ $self->{ INIT_BLOCKS } } };
}
#------------------------------------------------------------------------
# stash()
#
# Simple accessor methods to return the STASH values. This is likely
# to be called quite often so we provide a direct method rather than
# relying on the slower AUTOLOAD.
#------------------------------------------------------------------------
sub stash {
return $_[0]->{ STASH };
}
#------------------------------------------------------------------------
# AUTOLOAD
#
# Provides pseudo-methods for read-only access to various internal
# members. For example, templates(), plugins(), filters(),
# eval_perl(), load_perl(), etc. These aren't called very often, or
# may never be called at all.
#------------------------------------------------------------------------
sub AUTOLOAD {
my $self = shift;
my $method = $AUTOLOAD;
my $result;
$method =~ s/.*:://;
return if $method eq 'DESTROY';
warn "no such context method/member: $method\n"
unless defined ($result = $self->{ uc $method });
return $result;
}
#------------------------------------------------------------------------
# DESTROY
#
# Stash may contain references back to the Context via macro closures,
# etc. This breaks the circular references.
#------------------------------------------------------------------------
sub DESTROY {
my $self = shift;
undef $self->{ STASH };
}
#========================================================================
# -- PRIVATE METHODS --
#========================================================================
#------------------------------------------------------------------------
# _init(\%config)
#
# Initialisation method called by Template::Base::new()
#------------------------------------------------------------------------
sub _init {
my ($self, $config) = @_;
my ($name, $item, $method, $block, $blocks);
my @itemlut = (
LOAD_TEMPLATES => 'provider',
LOAD_PLUGINS => 'plugins',
LOAD_FILTERS => 'filters'
);
# LOAD_TEMPLATE, LOAD_PLUGINS, LOAD_FILTERS - lists of providers
while (($name, $method) = splice(@itemlut, 0, 2)) {
$item = $config->{ $name }
|| Template::Config->$method($config)
|| return $self->error($Template::Config::ERROR);
$self->{ $name } = ref $item eq 'ARRAY' ? $item : [ $item ];
}
my $providers = $self->{ LOAD_TEMPLATES };
my $prefix_map = $self->{ PREFIX_MAP } = $config->{ PREFIX_MAP } || { };
while (my ($key, $val) = each %$prefix_map) {
$prefix_map->{ $key } = [ map { $providers->[$_] } split(/\D+/, $val) ]
unless ref $val eq 'ARRAY';
# print(STDERR "prefix $key => $val => [",
# join(', ', @{ $prefix_map->{ $key } }), "]\n");
}
# STASH
$self->{ STASH } = $config->{ STASH } || do {
my $predefs = $config->{ VARIABLES }
|| $config->{ PRE_DEFINE }
|| { };
# hack to get stash to know about debug mode
$predefs->{ _DEBUG } = $config->{ DEBUG } || 0;
Template::Config->stash($predefs)
|| return $self->error($Template::Config::ERROR);
};
# compile any template BLOCKS specified as text
$blocks = $config->{ BLOCKS } || { };
$self->{ INIT_BLOCKS } = $self->{ BLOCKS } = {
map {
$block = $blocks->{ $_ };
$block = $self->template(\$block)
|| return undef
unless ref $block;
($_ => $block);
}
keys %$blocks
};
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# RECURSION - flag indicating is recursion into templates is supported
# EVAL_PERL - flag indicating if PERL blocks should be processed
# # DELIMITER - used to detect template prefixes
# TRIM - flag to remove leading and trailing whitespace from output
# BLKSTACK - list of hashes of BLOCKs defined in current template(s)
# CONFIG - original configuration hash
$self->{ RECURSION } = $config->{ RECURSION } || 0;
$self->{ EVAL_PERL } = $config->{ EVAL_PERL } || 0;
# $self->{ DELIMITER } = $config->{ DELIMITER } || ':';
$self->{ TRIM } = $config->{ TRIM } || 0;
$self->{ BLKSTACK } = [ ];
$self->{ CONFIG } = $config;
return $self;
}
#------------------------------------------------------------------------
# _dump()
#
# Debug method which returns a string representing the internal state
# of the context object.
#------------------------------------------------------------------------
sub _dump {
my $self = shift;
my $output = "$self\n";
foreach my $pname (qw( LOAD_TEMPLATES LOAD_PLUGINS LOAD_FILTERS )) {
foreach my $prov (@{ $self->{ $pname } }) {
$output .= $prov->_dump();
}
}
return $output;
}
1;
__END__
#------------------------------------------------------------------------
# IMPORTANT NOTE
# This documentation is generated automatically from source
# templates. Any changes you make here may be lost.
#
# The 'docsrc' documentation source bundle is available for download
# from http://www.template-toolkit.org/docs.html and contains all
# the source templates, XML files, scripts, etc., from which the
# documentation for the Template Toolkit is built.
#------------------------------------------------------------------------
=head1 NAME
Template::Context - Runtime context in which templates are processed
=head1 SYNOPSIS
use Template::Context;
# constructor
$context = Template::Context->new(\%config)
|| die $Template::Context::ERROR;
# fetch (load and compile) a template
$template = $context->template($template_name);
# fetch (load and instantiate) a plugin object
$plugin = $context->plugin($name, \@args);
# fetch (return or create) a filter subroutine
$filter = $context->filter($name, \@args, $alias);
# process/include a template, errors are thrown via die()
$output = $context->process($template, \%vars);
$output = $context->include($template, \%vars);
# raise an exception via die()
$context->throw($error_type, $error_message, \$output_buffer);
# catch an exception, clean it up and fix output buffer
$exception = $context->catch($exception, \$output_buffer);
# save/restore the stash to effect variable localisation
$new_stash = $context->localise(\%vars);
$old_stash = $context->delocalise();
# add new BLOCK or FILTER definitions
$context->define_block($name, $block);
$context->define_filter($name, \&filtersub, $is_dynamic);
# reset context, clearing any imported BLOCK definitions
$context->reset();
# methods for accessing internal items
$stash = $context->stash();
$tflag = $context->trim();
$epflag = $context->eval_perl();
$providers = $context->templates();
$providers = $context->plugins();
$providers = $context->filters();
...
=head1 DESCRIPTION
The Template::Context module defines an object class for representing
a runtime context in which templates are processed. It provides an
interface to the fundamental operations of the Template Toolkit
processing engine through which compiled templates (i.e. Perl code
constructed from the template source) can process templates, load
plugins and filters, raise exceptions and so on.
A default Template::Context object is created by the Template module.
Any Template::Context options may be passed to the Template new()
constructor method and will be forwarded to the Template::Context
constructor.
use Template;
my $template = Template->new({
TRIM => 1,
EVAL_PERL => 1,
BLOCKS => {
header => 'This is the header',
footer => 'This is the footer',
},
});
Similarly, the Template::Context constructor will forward all configuration
parameters onto other default objects (e.g. Template::Provider, Template::Plugins,
Template::Filters, etc.) that it may need to instantiate.
$context = Template::Context->new({
INCLUDE_PATH => '/home/abw/templates', # provider option
TAG_STYLE => 'html', # parser option
});
A Template::Context object (or subclass/derivative) can be explicitly
instantiated and passed to the Template new() constructor method as
the CONTEXT item.
use Template;
use Template::Context;
my $context = Template::Context->new({ TRIM => 1 });
my $template = Template->new({ CONTEXT => $context });
The Template module uses the Template::Config context() factory method
to create a default context object when required. The
$Template::Config::CONTEXT package variable may be set to specify an
alternate context module. This will be loaded automatically and its
new() constructor method called by the context() factory method when
a default context object is required.
use Template;
$Template::Config::CONTEXT = 'MyOrg::Template::Context';
my $template = Template->new({
EVAL_PERL => 1,
EXTRA_MAGIC => 'red hot', # your extra config items
...
});
=head1 METHODS
=head2 new(\%params)
The new() constructor method is called to instantiate a Template::Context
object. Configuration parameters may be specified as a HASH reference or
as a list of (name =E<gt> value) pairs.
my $context = Template::Context->new({
INCLUDE_PATH => 'header',
POST_PROCESS => 'footer',
});
my $context = Template::Context->new( EVAL_PERL => 1 );
The new() method returns a Template::Context object (or sub-class) or
undef on error. In the latter case, a relevant error message can be
retrieved by the error() class method or directly from the
$Template::Context::ERROR package variable.
my $context = Template::Context->new(\%config)
|| die Template::Context->error();
my $context = Template::Context->new(\%config)
|| die $Template::Context::ERROR;
The following configuration items may be specified.
=over 4
=item VARIABLES, PRE_DEFINE
The VARIABLES option (or PRE_DEFINE - they're equivalent) can be used
to specify a hash array of template variables that should be used to
pre-initialise the stash when it is created. These items are ignored
if the STASH item is defined.
my $context = Template::Context->new({
VARIABLES => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
or
my $context = Template::Context->new({
PRE_DEFINE => {
title => 'A Demo Page',
author => 'Joe Random Hacker',
version => 3.14,
},
};
=item BLOCKS
The BLOCKS option can be used to pre-define a default set of template
blocks. These should be specified as a reference to a hash array
mapping template names to template text, subroutines or Template::Document
objects.