[%#
# 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.
-%]
[% META book = 'Modules'
page = 'Filters'
%]
[% WRAPPER toc;
PROCESS tocitem
title ="SYNOPSIS"
subs = [];
PROCESS tocitem
title ="DESCRIPTION"
subs = [];
PROCESS tocitem
title ="METHODS"
subs = [
"new(\\%params) ",
"fetch(\$name, \\@args, \$context)"
];
PROCESS tocitem
title ="CONFIGURATION OPTIONS"
subs = [];
PROCESS tocitem
title ="TEMPLATE TOOLKIT FILTERS"
subs = [
"format(format)",
"upper",
"lower",
"ucfirst",
"lcfirst",
"trim",
"collapse",
"html",
"html_entity",
"html_para",
"html_break",
"uri",
"indent(pad)",
"truncate(length)",
"repeat(iterations)",
"remove(string) ",
"replace(search, replace) ",
"redirect(file)",
"eval(template_text)",
"perl(perlcode)",
"stdout(binmode)",
"stderr",
"null",
"latex(outputType)"
];
PROCESS tocitem
title ="AUTHOR"
subs = [];
PROCESS tocitem
title ="VERSION"
subs = [];
PROCESS tocitem
title ="COPYRIGHT"
subs = [];
PROCESS tocitem
title ="SEE ALSO"
subs = [];
END
%]
<!-- Pod to HTML conversion by the Template Toolkit version 2 -->
[% WRAPPER section
title="SYNOPSIS"
-%]<pre> use Template::Filters;</pre>
<pre> $filters = Template::Filters->new(\%config);</pre>
<pre> ($filter, $error) = $filters->fetch($name, \@args, $context);</pre>
[%- END %]
[% WRAPPER section
title="DESCRIPTION"
-%]<p>
The Template::Plugins module implements a provider for creating and/or
returning subroutines that implement the standard filters. Additional
custom filters may be provided via the FILTERS options.
</p>
[%- END %]
[% WRAPPER section
title="METHODS"
-%][% WRAPPER subsection
title = "new(\\%params) "
-%]<p>
Constructor method which instantiates and returns a reference to a
Template::Filters object. A reference to a hash array of configuration
items may be passed as a parameter. These are described below.
</p>
<pre> my $filters = Template::Filters->new({
FILTERS => { ... },
});</pre>
<pre> my $template = Template->new({
LOAD_FILTERS => [ $filters ],
});</pre>
<p>
A default Template::Filters module is created by the Template.pm module
if the LOAD_FILTERS option isn't specified. All configuration parameters
are forwarded to the constructor.
</p>
<pre> $template = Template->new({
FILTERS => { ... },
});</pre>
[%- END %]
[% WRAPPER subsection
title = "fetch(\$name, \\@args, \$context)"
-%]<p>
Called to request that a filter of a given name be provided. The name
of the filter should be specified as the first parameter. This should
be one of the standard filters or one specified in the FILTERS
configuration hash. The second argument should be a reference to an
array containing configuration parameters for the filter. This may be
specified as 0, or undef where no parameters are provided. The third
argument should be a reference to the current Template::Context
object.
</p>
<p>
The method returns a reference to a filter sub-routine on success. It
may also return (undef, STATUS_DECLINE) to decline the request, to allow
delegation onto other filter providers in the LOAD_FILTERS chain of
responsibility. On error, ($error, STATUS_ERROR) is returned where $error
is an error message or Template::Exception object indicating the error
that occurred.
</p>
<p>
When the TOLERANT option is set, errors are automatically downgraded to
a STATUS_DECLINE response.
</p>
[%- END %]
[%- END %]
[% WRAPPER section
title="CONFIGURATION OPTIONS"
-%]<p>
The following list details the configuration options that can be provided
to the Template::Filters new() constructor.
</p>
<ul>
<li><b>FILTERS</b><br>
<p>
The FILTERS option can be used to specify custom filters which can
then be used with the FILTER directive like any other. These are
added to the standard filters which are available by default. Filters
specified via this option will mask any standard filters of the same
name.
</p>
<p>
The FILTERS option should be specified as a reference to a hash array
in which each key represents the name of a filter. The corresponding
value should contain a reference to an array containing a subroutine
reference and a flag which indicates if the filter is static (0) or
dynamic (1). A filter may also be specified as a solitary subroutine
reference and is assumed to be static.
</p>
<pre> $filters = Template::Filters->new({
FILTERS => {
'sfilt1' => \&static_filter, # static
'sfilt2' => [ \&static_filter, 0 ], # same as above
'dfilt1' => [ \&dyanamic_filter_factory, 1 ],
},
});</pre>
<p>
Additional filters can be specified at any time by calling the
define_filter() method on the current Template::Context object.
The method accepts a filter name, a reference to a filter
subroutine and an optional flag to indicate if the filter is
dynamic.
</p>
<pre> my $context = $template->context();
$context->define_filter('new_html', \&new_html);
$context->define_filter('new_repeat', \&new_repeat, 1);</pre>
<p>
Static filters are those where a single subroutine reference is used
for all invocations of a particular filter. Filters that don't accept
any configuration parameters (e.g. 'html') can be implemented
statically. The subroutine reference is simply returned when that
particular filter is requested. The subroutine is called to filter
the output of a template block which is passed as the only argument.
The subroutine should return the modified text.
</p>
<pre> sub static_filter {
my $text = shift;
# do something to modify $text...
return $text;
}</pre>
<p>
The following template fragment:
</p>
<pre> [% tt_start_tag %] FILTER sfilt1 [% tt_end_tag %]
Blah blah blah.
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
is approximately equivalent to:
</p>
<pre> &static_filter("\nBlah blah blah.\n");</pre>
<p>
Filters that can accept parameters (e.g. 'truncate') should be
implemented dynamically. In this case, the subroutine is taken to be
a filter 'factory' that is called to create a unique filter subroutine
each time one is requested. A reference to the current
Template::Context object is passed as the first parameter, followed by
any additional parameters specified. The subroutine should return
another subroutine reference (usually a closure) which implements the
filter.
</p>
<pre> sub dynamic_filter_factory {
my ($context, @args) = @_;</pre>
<pre> return sub {
my $text = shift;
# do something to modify $text...
return $text;
}
}</pre>
<p>
The following template fragment:
</p>
<pre> [% tt_start_tag %] FILTER dfilt1(123, 456) [% tt_end_tag %]
Blah blah blah
[% tt_start_tag %] END [% tt_end_tag %] </pre>
<p>
is approximately equivalent to:
</p>
<pre> my $filter = &dynamic_filter_factory($context, 123, 456);
&$filter("\nBlah blah blah.\n");</pre>
<p>
See the FILTER directive for further examples.
</p>
<li><b>TOLERANT</b><br>
<p>
The TOLERANT flag is used by the various Template Toolkit provider
modules (Template::Provider, Template::Plugins, Template::Filters) to
control their behaviour when errors are encountered. By default, any
errors are reported as such, with the request for the particular
resource (template, plugin, filter) being denied and an exception
raised. When the TOLERANT flag is set to any true values, errors will
be silently ignored and the provider will instead return
STATUS_DECLINED. This allows a subsequent provider to take
responsibility for providing the resource, rather than failing the
request outright. If all providers decline to service the request,
either through tolerated failure or a genuine disinclination to
comply, then a '<resource> not found' exception is raised.
</p>
</ul>
[%- END %]
[% WRAPPER section
title="TEMPLATE TOOLKIT FILTERS"
-%]<p>
The following standard filters are distributed with the Template Toolkit.
</p>
[% WRAPPER subsection
title = "format(format)"
-%]<p>
The 'format' filter takes a format string as a parameter (as per
printf()) and formats each line of text accordingly.
</p>
<pre> [% tt_start_tag %] FILTER format('<!-- %-40s -->') [% tt_end_tag %]
This is a block of text filtered
through the above format.
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> <!-- This is a block of text filtered -->
<!-- through the above format. --></pre>
[%- END %]
[% WRAPPER subsection
title = "upper"
-%]<p>
Folds the input to UPPER CASE.
</p>
<pre> [% tt_start_tag %] "hello world" FILTER upper [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> HELLO WORLD</pre>
[%- END %]
[% WRAPPER subsection
title = "lower"
-%]<p>
Folds the input to lower case.
</p>
<pre> [% tt_start_tag %] "Hello World" FILTER lower [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> hello world</pre>
[%- END %]
[% WRAPPER subsection
title = "ucfirst"
-%]<p>
Folds the first character of the input to UPPER CASE.
</p>
<pre> [% tt_start_tag %] "hello" FILTER ucfirst [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> Hello</pre>
[%- END %]
[% WRAPPER subsection
title = "lcfirst"
-%]<p>
Folds the first character of the input to lower case.
</p>
<pre> [% tt_start_tag %] "HELLO" FILTER lcfirst [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> hELLO</pre>
[%- END %]
[% WRAPPER subsection
title = "trim"
-%]<p>
Trims any leading or trailing whitespace from the input text. Particularly
useful in conjunction with INCLUDE, PROCESS, etc., having the same effect
as the TRIM configuration option.
</p>
<pre> [% tt_start_tag %] INCLUDE myfile | trim [% tt_end_tag %]</pre>
[%- END %]
[% WRAPPER subsection
title = "collapse"
-%]<p>
Collapse any whitespace sequences in the input text into a single space.
Leading and trailing whitespace (which would be reduced to a single space)
is removed, as per trim.
</p>
<pre> [% tt_start_tag %] FILTER collapse [% tt_end_tag %]</pre>
<pre> The cat</pre>
<pre> sat on</pre>
<pre> the mat</pre>
<pre> [% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> The cat sat on the mat</pre>
[%- END %]
[% WRAPPER subsection
title = "html"
-%]<p>
Converts the characters '<', '>' and '&' to '&lt;', '&gt;' and
'&amp;', respectively, protecting them from being interpreted as
representing HTML tags or entities.
</p>
<pre> [% tt_start_tag %] FILTER html [% tt_end_tag %]
Binary "<=>" returns -1, 0, or 1 depending on...
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> Binary "&lt;=&gt;" returns -1, 0, or 1 depending on...</pre>
[%- END %]
[% WRAPPER subsection
title = "html_entity"
-%]<p>
The html filter is fast and simple but it doesn't encode the full
range of HTML entities that your text may contain. The html_entity
filter uses either the Apache::Util module (which is written in C and
is therefore faster) or the HTML::Entities module (written in Perl but
equally as comprehensive) to perform the encoding. If one or other of
these modules are installed on your system then the text will be
encoded (via the escape_html() or encode_entities() subroutines
respectively) to convert all extended characters into their
appropriate HTML entities (e.g. converting 'é' to '&eacute;'). If
neither module is available on your system then an 'html_all' exception
will be thrown reporting an appropriate message.
</p>
<p>
For further information on HTML entity encoding, see
http://www.w3.org/TR/REC-html40/sgml/entities.html.
</p>
[%- END %]
[% WRAPPER subsection
title = "html_para"
-%]<p>
This filter formats a block of text into HTML paragraphs. A sequence of
two or more newlines is used as the delimiter for paragraphs which are
then wrapped in HTML <p>...</p> tags.
</p>
<pre> [% tt_start_tag %] FILTER html_para [% tt_end_tag %]
The cat sat on the mat.</pre>
<pre> Mary had a little lamb.
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> <p>
The cat sat on the mat.
</p></pre>
<pre> <p>
Mary had a little lamb.
</p></pre>
[%- END %]
[% WRAPPER subsection
title = "html_break"
-%]<p>
Similar to the html_para filter described above, but uses the HTML tag
sequence <br><br> to join paragraphs.
</p>
<pre> [% tt_start_tag %] FILTER html_break [% tt_end_tag %]
The cat sat on the mat.</pre>
<pre> Mary had a little lamb.
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> The cat sat on the mat.
<br>
<br>
Mary had a little lamb.</pre>
[%- END %]
[% WRAPPER subsection
title = "uri"
-%]<p>
This filter URI escapes the input text, converting any characters
outside of the permitted URI character set (as defined by RFC 2396)
into a <code>'%nn'</code> hex escape.
</p>
<pre> [% tt_start_tag %] 'my file.html' | uri [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> my%20file.html</pre>
<p>
Note that URI escaping isn't always enough when generating hyperlinks in
an HTML document. The <code>'&'</code> character, for example, is valid in a URI and
will not be escaped by the URI filter. In this case you should also filter
the text through the 'html' filter.
</p>
<pre> <a href="[% tt_start_tag %] filename | uri | html [% tt_end_tag %]">click here</a></pre>
[%- END %]
[% WRAPPER subsection
title = "indent(pad)"
-%]<p>
Indents the text block by a fixed pad string or width. The 'pad' argument
can be specified as a string, or as a numerical value to indicate a pad
width (spaces). Defaults to 4 spaces if unspecified.
</p>
<pre> [% tt_start_tag %] FILTER indent('ME> ') [% tt_end_tag %]
blah blah blah
cabbages, rhubard, onions
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> ME> blah blah blah
ME> cabbages, rhubard, onions</pre>
[%- END %]
[% WRAPPER subsection
title = "truncate(length)"
-%]<p>
Truncates the text block to the length specified, or a default length of
32. Truncated text will be terminated with '...' (i.e. the '...' falls
inside the required length, rather than appending to it).
</p>
<pre> [% tt_start_tag %] FILTER truncate(21) [% tt_end_tag %]
I have much to say on this matter that has previously
been said on more than one occasion.
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> I have much to say...</pre>
[%- END %]
[% WRAPPER subsection
title = "repeat(iterations)"
-%]<p>
Repeats the text block for as many iterations as are specified (default: 1).
</p>
<pre> [% tt_start_tag %] FILTER repeat(3) [% tt_end_tag %]
We want more beer and we want more beer,
[% tt_start_tag %] END [% tt_end_tag %]
We are the more beer wanters!</pre>
<p>
output:
</p>
<pre> We want more beer and we want more beer,
We want more beer and we want more beer,
We want more beer and we want more beer,
We are the more beer wanters!</pre>
[%- END %]
[% WRAPPER subsection
title = "remove(string) "
-%]<p>
Searches the input text for any occurrences of the specified string and
removes them. A Perl regular expression may be specified as the search
string.
</p>
<pre> [% tt_start_tag %] "The cat sat on the mat" FILTER remove('\s+') [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> Thecatsatonthemat</pre>
[%- END %]
[% WRAPPER subsection
title = "replace(search, replace) "
-%]<p>
Similar to the remove filter described above, but taking a second parameter
which is used as a replacement string for instances of the search string.
</p>
<pre> [% tt_start_tag %] "The cat sat on the mat" | replace('\s+', '_') [% tt_end_tag %]</pre>
<p>
output:
</p>
<pre> The_cat_sat_on_the_mat</pre>
[%- END %]
[% WRAPPER subsection
title = "redirect(file)"
-%]<p>
The 'redirect' filter redirects the output of the block into a separate
file, specified relative to the OUTPUT_PATH configuration item.
</p>
<pre> [% tt_start_tag %] FOREACH user = myorg.userlist [% tt_end_tag %]
[% tt_start_tag %] FILTER redirect("users/${user.id}.html") [% tt_end_tag %]
[% tt_start_tag %] INCLUDE userinfo [% tt_end_tag %]
[% tt_start_tag %] END [% tt_end_tag %]
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
or more succinctly, using side-effect notation:
</p>
<pre> [% tt_start_tag %] INCLUDE userinfo
FILTER redirect("users/${user.id}.html")
FOREACH user = myorg.userlist
[% tt_end_tag %]</pre>
<p>
A 'file' exception will be thrown if the OUTPUT_PATH option is undefined.
</p>
[%- END %]
[% WRAPPER subsection
title = "eval(template_text)"
-%]<p>
The 'eval' filter evaluates the block as template text, processing
any directives embedded within it. This allows template variables to
contain template fragments, or for some method to be provided for
returning template fragments from an external source such as a
database, which can then be processed in the template as required.
</p>
<pre> my $vars = {
fragment => "The cat sat on the [% tt_start_tag %] place [% tt_end_tag %]",
};
$template->process($file, $vars);</pre>
<p>
The following example:
</p>
<pre> [% tt_start_tag %] fragment | eval [% tt_end_tag %]</pre>
<p>
is therefore equivalent to
</p>
<pre> The cat sat on the [% tt_start_tag %] place [% tt_end_tag %]</pre>
<p>
The 'evaltt' filter is provided as an alias for 'eval'.
</p>
[%- END %]
[% WRAPPER subsection
title = "perl(perlcode)"
-%]<p>
The 'perl' filter evaluates the block as Perl code. The EVAL_PERL
option must be set to a true value or a 'perl' exception will be
thrown.
</p>
<pre> [% tt_start_tag %] my_perl_code | perl [% tt_end_tag %]</pre>
<p>
In most cases, the [% tt_start_tag %] PERL [% tt_end_tag %] ... [% tt_start_tag %] END [% tt_end_tag %] block should suffice for
evaluating Perl code, given that template directives are processed
before being evaluate as Perl. Thus, the previous example could have
been written in the more verbose form:
</p>
<pre> [% tt_start_tag %] PERL [% tt_end_tag %]
[% tt_start_tag %] my_perl_code [% tt_end_tag %]
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
as well as
</p>
<pre> [% tt_start_tag %] FILTER perl [% tt_end_tag %]
[% tt_start_tag %] my_perl_code [% tt_end_tag %]
[% tt_start_tag %] END [% tt_end_tag %]</pre>
<p>
The 'evalperl' filter is provided as an alias for 'perl' for backwards
compatibility.
</p>
[%- END %]
[% WRAPPER subsection
title = "stdout(binmode)"
-%]<p>
The stdout filter prints the output generated by the enclosing block to
STDOUT. If binmode is set, binary mode on STDOUT is turned on (see the
binmode perl function.
</p>
<p>
The stdout filter can be used to force binmode on STDOUT, or also inside
redirect, null or stderr blocks to make sure that particular output goes
to stdout. See the null filter below for an example.
</p>
[%- END %]
[% WRAPPER subsection
title = "stderr"
-%]<p>
The stderr filter prints the output generated by the enclosing block to
STDERR.
</p>
[%- END %]
[% WRAPPER subsection
title = "null"
-%]<p>
The null filter prints nothing. This is useful for plugins whose
methods return values that you don't want to appear in the output.
Rather than assigning every plugin method call to a dummy variable
to silence it, you can wrap the block in a null filter:
</p>
<pre> [% tt_start_tag %] FILTER null;
USE im = GD.Image(100,100);
black = im.colorAllocate(0, 0, 0);
red = im.colorAllocate(255,0, 0);
blue = im.colorAllocate(0, 0, 255);
im.arc(50,50,95,75,0,360,blue);
im.fill(50,50,red);
im.png | stdout(1);
END;
-[% tt_end_tag %]</pre>
<p>
Notice the use of the stdout filter to ensure that a particular expression
generates output to stdout (in this case in binary mode).
</p>
[%- END %]
[% WRAPPER subsection
title = "latex(outputType)"
-%]<p>
Passes the text block to LaTeX and produces either PDF, DVI or
PostScript output. The 'outputType' argument determines the output
format and it should be set to one of the strings: "pdf" (default),
"dvi", or "ps".
</p>
<p>
The text block should be a complete LaTeX source file.
</p>
<pre> [% tt_start_tag %] FILTER latex("pdf") -[% tt_end_tag %]
\documentclass{article}</pre>
<pre> \begin{document}</pre>
<pre> \title{A Sample TT2 \LaTeX\ Source File}
\author{Craig Barratt}
\maketitle</pre>
<pre> \section{Introduction}
This is some text.</pre>
<pre> \end{document}
[% tt_start_tag %] END -[% tt_end_tag %]</pre>
<p>
The output will be a PDF file. You should be careful not to prepend or
append any extraneous characters or text outside the FILTER block,
since this text will wrap the (binary) output of the latex filter.
Notice the END directive uses '-[% tt_end_tag %]' for the END_TAG to remove the
trailing new line.
</p>
<p>
One example where you might prepend text is in a CGI script where
you might include the Content-Type before the latex output, eg:
</p>
<pre> Content-Type: application/pdf</pre>
<pre> [% tt_start_tag %] FILTER latex("pdf") -[% tt_end_tag %]
\documentclass{article}
\begin{document}
...
\end{document}
[% tt_start_tag %] END -[% tt_end_tag %]</pre>
<p>
In other cases you might use the redirect filter to put the output
into a file, rather than delivering it to stdout. This might be
suitable for batch scripts:
</p>
<pre> [% tt_start_tag %] output = FILTER latex("pdf") -[% tt_end_tag %]
\documentclass{article}
\begin{document}
...
\end{document}
[% tt_start_tag %] END; output | redirect("document.pdf", 1) -[% tt_end_tag %]</pre>
<p>
(Notice the second argument to redirect to force binary mode.)
</p>
<p>
Note that the latex filter runs one or two external programs, so it
isn't very fast. But for modest documents the performance is adequate,
even for interactive applications.
</p>
<p>
A error of type 'latex' will be thrown if there is an error reported
by latex, pdflatex or dvips.
</p>
[%- END %]
[%- END %]
[% WRAPPER section
title="AUTHOR"
-%]<p>
Andy Wardley <abw@andywardley.com>
</p>
<p>
[% ttlink('http://www.andywardley.com/', 'http://www.andywardley.com/') -%]
</p>
[%- END %]
[% WRAPPER section
title="VERSION"
-%]<p>
2.58, distributed as part of the
Template Toolkit version 2.08, released on 30 July 2002.
</p>
[%- END %]
[% WRAPPER section
title="COPYRIGHT"
-%]<pre> Copyright (C) 1996-2002 Andy Wardley. All Rights Reserved.
Copyright (C) 1998-2002 Canon Research Centre Europe Ltd.</pre>
<p>
This module is free software; you can redistribute it and/or
modify it under the same terms as Perl itself.
</p>
[%- END %]
[% WRAPPER section
title="SEE ALSO"
-%]<p>
[% ttlink('Template', 'Template') -%], [% ttlink('Template::Context', 'Template::Context') -%], [% ttlink('Template::Manual::Filters', 'Template::Manual::Filters') -%]
</p>
[%- END %]