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#============================================================= -*-perl-*-
# Template
# Module implementing a simple, user-oriented front-end to the Template
# Toolkit.
# Andy Wardley <>
# Copyright (C) 1996-2014 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.
package Template;
use strict;
use warnings;
use 5.006;
use base 'Template::Base';
use Template::Config;
use Template::Constants;
use Template::Provider;
use Template::Service;
use File::Basename;
use File::Path;
use Scalar::Util qw(blessed);
our $VERSION = '2.27';
our $ERROR = '';
our $DEBUG = 0;
our $BINMODE = 0 unless defined $BINMODE;
# preload all modules if we're running under mod_perl
Template::Config->preload() if $ENV{ MOD_PERL };
# process($input, \%replace, $output)
# Main entry point for the Template Toolkit. The Template module
# delegates most of the processing effort to the underlying SERVICE
# object, an instance of the Template::Service class.
sub process {
my ($self, $template, $vars, $outstream, @opts) = @_;
my ($output, $error);
my $options = (@opts == 1) && ref($opts[0]) eq 'HASH'
? shift(@opts) : { @opts };
$options->{ binmode } = $BINMODE
unless defined $options->{ binmode };
# we're using this for testing in t/output.t and t/filter.t so
# don't remove it if you don't want tests to fail...
$self->DEBUG("set binmode\n") if $DEBUG && $options->{ binmode };
$output = $self->{ SERVICE }->process($template, $vars);
if (defined $output) {
$outstream ||= $self->{ OUTPUT };
unless (ref $outstream) {
my $outpath = $self->{ OUTPUT_PATH };
$outstream = "$outpath/$outstream" if $outpath;
# send processed template to output stream, checking for error
return ($self->error($error))
if ($error = &_output($outstream, \$output, $options));
return 1;
else {
return $self->error($self->{ SERVICE }->error);
# service()
# Returns a reference to the internal SERVICE object which handles
# all requests for this Template object
sub service {
my $self = shift;
return $self->{ SERVICE };
# context()
# Returns a reference to the CONTEXT object within the SERVICE
# object.
sub context {
my $self = shift;
return $self->{ SERVICE }->{ CONTEXT };
sub template {
# _init(\%config)
sub _init {
my ($self, $config) = @_;
# convert any textual DEBUG args to numerical form
my $debug = $config->{ DEBUG };
$config->{ DEBUG } = Template::Constants::debug_flags($self, $debug)
|| return if defined $debug && $debug !~ /^\d+$/;
# prepare a namespace handler for any CONSTANTS definition
if (my $constants = $config->{ CONSTANTS }) {
my $ns = $config->{ NAMESPACE } ||= { };
my $cns = $config->{ CONSTANTS_NAMESPACE } || 'constants';
$constants = Template::Config->constants($constants)
|| return $self->error(Template::Config->error);
$ns->{ $cns } = $constants;
$self->{ SERVICE } = $config->{ SERVICE }
|| Template::Config->service($config)
|| return $self->error(Template::Config->error);
$self->{ OUTPUT } = $config->{ OUTPUT } || \*STDOUT;
$self->{ OUTPUT_PATH } = $config->{ OUTPUT_PATH };
return $self;
# _output($where, $text)
sub _output {
my ($where, $textref, $options) = @_;
my $reftype;
my $error = 0;
# call a CODE reference
if (($reftype = ref($where)) eq 'CODE') {
# print to a glob (such as \*STDOUT)
elsif ($reftype eq 'GLOB') {
print $where $$textref;
# append output to a SCALAR ref
elsif ($reftype eq 'SCALAR') {
$$where .= $$textref;
# push onto ARRAY ref
elsif ($reftype eq 'ARRAY') {
push @$where, $$textref;
# call the print() method on an object that implements the method
# (e.g. IO::Handle, Apache::Request, etc)
elsif (blessed($where) && $where->can('print')) {
# a simple string is taken as a filename
elsif (! $reftype) {
local *FP;
# make destination directory if it doesn't exist
my $dir = dirname($where);
eval { mkpath($dir) unless -d $dir; };
if ($@) {
# strip file name and line number from error raised by die()
($error = $@) =~ s/ at \S+ line \d+\n?$//;
elsif (open(FP, ">$where")) {
# binmode option can be 1 or a specific layer, e.g. :utf8
my $bm = $options->{ binmode };
if ($bm && $bm eq 1) {
binmode FP;
elsif ($bm){
binmode FP, $bm;
print FP $$textref;
close FP;
else {
$error = "$where: $!";
# give up, we've done our best
else {
$error = "output_handler() cannot determine target type ($where)\n";
return $error;
=head1 NAME
Template - Front-end module to the Template Toolkit
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();
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 L<Template::Manual> for the complete reference
manual which goes into much greater depth about the features and use
of the Template Toolkit. The L<Template::Tutorial> is also available
as an introductory guide to using the Template Toolkit.
=head1 METHODS
=head2 new(\%config)
The C<new()> constructor method (implemented by the
L<Template::Base|Template::Base#new()> base class) instantiates a new
C<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',
}) || die $Template::ERROR, "\n";
A reference to a new C<Template> object is returned, or undef on error. In the
latter case, the error message can be retrieved by calling L<error()> as a
class method or by examining the C<$Template::ERROR> package variable
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 $Template::ERROR, "\n";
=head2 process($template, \%vars, $output, %options)
The C<process()> method is called to process a template. The first parameter
indicates the input template as one of: a filename relative to
C<INCLUDE_PATH>, if defined; a reference to a text string containing the
template text; or a file handle reference (e.g. C<IO::Handle> or sub-class) or
C<GLOB> (e.g. C<\*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.
# filename
|| die $tt->error(), "\n";
# text reference
$text = "[% INCLUDE header %]\nHello world!\n[% INCLUDE footer %]";
|| die $tt->error(), "\n";
# file handle (GLOB)
|| die $tt->error(), "\n";
[% 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 C<STDOUT>. The
C<process()> method then returns C<1> to indicate success. A third parameter
may be passed to the C<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 C<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
C<print()> method (e.g. C<IO::Handle>, C<Apache::Request>, etc.) which will be called,
passing the generated output as a parameter.
# 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;
# ...your code here...
# direct output to Apache::Request via $req->print($output)
$tt->process($file, $vars, $req) || do {
return OK;
After the optional third output argument can come an optional
reference to a hash or a list of C<(name, value)> pairs providing further
options for the output. The only option currently supported is
C<binmode> which, when set to any true value will ensure that files
created (but not any existing file handles passed) will be set to
binary mode.
# either: hash reference of options
$tt->process($infile, $vars, $outfile, { binmode => 1 })
|| die $tt->error(), "\n";
# or: list of name, value pairs
$tt->process($infile, $vars, $outfile, binmode => 1)
|| die $tt->error(), "\n";
Alternately, the C<binmode> argument can specify a particular IO layer such
as C<:utf8>.
$tt->process($infile, $vars, $outfile, binmode => ':utf8')
|| die $tt->error(), "\n";
The C<OUTPUT> configuration item can be used to specify a default output
location other than C<\*STDOUT>. The C<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 $tt->error(), "\n";
The C<process()> method returns C<1> on success or C<undef> on error. The
error message generated in the latter case can be retrieved by calling the
L<error()> method. See also L<CONFIGURATION SUMMARY> which describes how error
handling may be further customised.
=head2 error()
When called as a class method, it returns the value of the C<$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
C<_ERROR> variable, as set by an error condition in a previous call to
|| die $tt->error(), "\n";
Errors are represented in the Template Toolkit by objects of the
L<Template::Exception> class. If the L<process()> method returns a false value
then the C<error()> method can be called to return an object of this class.
The L<type()|Template::Exception#type()> and
L<info()|Template::Exception#info()> methods can called on the object to
retrieve the error type and information string, respectively. The
method can be called to return a string of the form C<$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";
=head2 service()
The C<Template> module delegates most of the effort of processing templates
to an underlying L<Template::Service> object. This method returns a reference
to that object.
=head2 context()
The L<Template::Service> module uses a core L<Template::Context> object for
runtime processing of templates. This method returns a reference to
that object and is equivalent to C<< $template-E<gt>service-E<gt>context() >>.
=head2 template($name)
This method is a simple wrapper around the L<Template::Context> method of the
same name. It returns a compiled template for the source provided as an
The following list gives a short summary of each Template Toolkit
configuration option. See L<Template::Manual::Config> for full details.
=head2 Template Style and Parsing Options
Specifies the character encoding.
Define tokens that indicate start and end of directives
(default: 'C<[%>' and 'C<%]>').
=head3 TAG_STYLE
Set C<START_TAG> and C<END_TAG> according to a pre-defined style (default:
'C<template>', as above).
Removes whitespace before/after directives (default: 0/0).
=head3 TRIM
Remove leading and trailing whitespace from template output (default: 0).
Interpolate variables embedded like C<$this> or C<${this}> (default: 0).
=head3 ANYCASE
Allow directive keywords in lower case (default: 0 - UPPER only).
=head2 Template Files and Blocks
One or more directories to search for templates.
Delimiter for separating paths in C<INCLUDE_PATH> (default: 'C<:>').
Allow absolute file names, e.g. C</foo/bar.html> (default: 0).
Allow relative filenames, e.g. C<../foo/bar.html> (default: 0).
=head3 DEFAULT
Default template to use when another not found.
=head3 BLOCKS
Hash array pre-defining template blocks.
Enabled by default causing C<BLOCK> definitions to be reset each time a
template is processed. Disable to allow C<BLOCK> definitions to persist.
Flag to permit recursion into templates (default: 0).
=head2 Template Variables
Hash array of variables and values to pre-define in the stash.
=head2 Runtime Processing Options
=head3 EVAL_PERL
Flag to indicate if C<PERL>/C<RAWPERL> blocks should be processed (default: 0).
Name of template(s) to process before/after main template.
=head3 PROCESS
Name of template(s) to process instead of main template.
=head3 ERROR
Name of error template or reference to hash array mapping error types to
=head3 OUTPUT
Default output location or handler.
Directory into which output files can be written.
=head3 DEBUG
Enable debugging messages.
=head2 Caching and Compiling Options
Maximum number of compiled templates to cache in memory (default:
undef - cache all)
Filename extension for compiled template files (default: undef - don't
Root of directory in which compiled template files should be written
(default: undef - don't compile).
=head2 Plugins and Filters
=head3 PLUGINS
Reference to a hash array mapping plugin names to Perl packages.
One or more base classes under which plugins may be found.
=head3 LOAD_PERL
Flag to indicate regular Perl modules should be loaded if a named plugin
can't be found (default: 0).
=head3 FILTERS
Hash array mapping filter names to filter subroutines or factories.
=head2 Customisation and Extension
List of template providers.
List of plugin providers.
List of filter providers.
Set providers to tolerate errors as declinations (default: 0).
=head3 SERVICE
Reference to a custom service object (default: L<Template::Service>).
=head3 CONTEXT
Reference to a custom context object (default: L<Template::Context>).
=head3 STASH
Reference to a custom stash object (default: L<Template::Stash>).
=head3 PARSER
Reference to a custom parser object (default: L<Template::Parser>).
=head3 GRAMMAR
Reference to a custom grammar object (default: L<Template::Grammar>).
The following list gives a short summary of each Template Toolkit directive.
See L<Template::Manual::Directives> for full details.
=head2 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" %]
=head2 CALL
As per L<GET> but without printing result (e.g. call code)
[% CALL variable %]
=head2 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, ... }
=head2 DEFAULT
Like L<SET>, but variables are only set if currently unset (i.e. have no
true value).
[% DEFAULT variable = value %]
=head2 INSERT
Insert a file without any processing performed on the contents.
[% INSERT legalese.txt %]
=head2 PROCESS
Process another template file or block and insert the generated output.
Any template L<BLOCK>s or variables defined or updated in the C<PROCESS>ed
template will thereafter be defined in the calling template.
[% PROCESS template %]
[% PROCESS template var = val, ... %]
=head2 INCLUDE
Similar to C<PROCESS>, but using a local copy of the current variables.
Any template C<BLOCK>s or variables defined in the C<INCLUDE>d template
remain local to it.
[% INCLUDE template %]
[% INCLUDE template var = val, ... %]
=head2 WRAPPER
The content between the C<WRAPPER> and corresponding C<END> directives is first
evaluated, with the output generated being stored in the C<content> variable.
The named template is then process as per C<INCLUDE>.
[% WRAPPER layout %]
Some template markup [% blah %]...
[% END %]
A simple F<layout> template might look something like this:
Your header here...
[% content %]
Your footer here...
=head2 BLOCK
Define a named template block for L<INCLUDE>, L<PROCESS> and L<WRAPPER>
to use.
[% BLOCK hello %]
Hello World
[% END %]
[% INCLUDE hello %]
=head2 FOREACH
Repeat the enclosed C<FOREACH> ... C<END> block for each value in the list.
[% FOREACH variable IN [ val, val, val ] %] # either
[% FOREACH variable IN list %] # or
The variable is set to [% variable %]
[% END %]
=head2 WHILE
The block enclosed between C<WHILE> and C<END> block is processed while
the specified condition is true.
[% WHILE condition %]
[% END %]
The enclosed block is processed if the condition is true / false.
[% IF condition %]
[% ELSIF condition %]
[% ELSE %]
[% END %]
[% UNLESS condition %]
[% # ELSIF/ELSE as per IF, above %]
[% END %]
=head2 SWITCH / CASE
Multi-way switch/case statement.
[% SWITCH variable %]
[% CASE val1 %]
[% CASE [ val2, val3 ] %]
[% CASE %] # or [% CASE DEFAULT %]
[% END %]
=head2 MACRO
Define a named macro.
[% MACRO name <directive> %]
[% MACRO name(arg1, arg2) <directive> %]
[% name %]
[% name(val1, val2) %]
=head2 FILTER
Process enclosed C<FILTER> ... C<END> block then pipe through a filter.
[% FILTER name %] # either
[% FILTER name( params ) %] # or
[% FILTER alias = name( params ) %] # or
[% END %]
=head2 USE
Load a plugin module (see C<Template::<Manual::Plugins>), or any regular Perl
module when the C<LOAD_PERL> option is set.
[% USE name %] # either
[% USE name( params ) %] # or
[% USE var = name( params ) %] # or
[% name.method %]
[% var.method %]
Evaluate enclosed blocks as Perl code (requires the C<EVAL_PERL> option to be
[% PERL %]
# perl code goes here
$stash->set('foo', 10);
print "set 'foo' to ", $stash->get('foo'), "\n";
print $context->include('footer', { var => $val });
[% END %]
# raw perl code goes here, no magic but fast.
$output .= 'some output';
[% END %]
Exception handling.
[% TRY %]
[% THROW type info %]
[% CATCH type %]
catch content
[% error.type %] [% %]
[% CATCH %] # or [% CATCH DEFAULT %]
[% FINAL %]
this block is always processed
[% END %]
=head2 NEXT
Jump straight to the next item in a C<FOREACH> or C<WHILE> loop.
[% NEXT %]
=head2 LAST
Break out of C<FOREACH> or C<WHILE> loop.
[% LAST %]
=head2 RETURN
Stop processing current template and return to including templates.
[% RETURN %]
=head2 STOP
Stop processing all templates and return to caller.
[% STOP %]
=head2 TAGS
Define new tag style or characters (default: C<[%> C<%]>).
[% TAGS html %]
[% TAGS <!-- --> %]
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
The source code for the Template Toolkit is held in a public git repository
on Github: L<>
=head1 AUTHOR
Andy Wardley E<lt>abw@wardley.orgE<gt> L<>
=head1 VERSION
Template Toolkit version 2.26, released January 2014.
Copyright (C) 1996-2014 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.
# Local Variables:
# mode: perl
# perl-indent-level: 4
# indent-tabs-mode: nil
# End:
# vim: expandtab shiftwidth=4: