template::filters(3)

NAME

Template::Filters - Post-processing filters for template
blocks

SYNOPSIS

use Template::Filters;
$filters = Template::Filters->new(config);
($filter,  $error)  =  $filters->fetch($name,   @args,
$context);

DESCRIPTION

The Template::Plugins module implements a provider for
creating and/or returning subroutines that implement the
standard filters. Additional custom filters may be pro
vided via the FILTERS options.

METHODS

new%(params)

Constructor method which instantiates and returns a refer ence to a Template::Filters object. A reference to a hash array of configuration items may be passed as a parameter. These are described below.: my $filters = Template::Filters->new({
FILTERS => { ... },; });; my $template = Template->new({
LOAD_FILTERS => [ $filters ],; });
A default Template::Filters module is created by the Tem plate.pm module if the LOAD_FILTERS option isn't speci fied. All configuration parameters are forwarded to the constructor.: $template = Template->new({
FILTERS => { ... },; });
fetch($name,@args, $context)
Called to request that a filter of a given name be pro vided. The name of the filter should be specified as the first parameter. This should be one of the standard fil ters or one specified in the FILTERS configuration hash. The second argument should be a reference to an array con taining configuration parameters for the filter. This may be specified as 0, or undef where no parameters are pro vided. The third argument should be a reference to the current Template::Context object.
The method returns a reference to a filter sub-routine on success. It may also return (undef, STATUS_DECLINE) to decline the request, to allow delegation onto other filter providers in the LOAD_FILTERS chain of responsibility. On error, ($error, STATUS_ERROR) is returned where $error is an error message or Template::Exception object indicating the error that occurred.
When the TOLERANT option is set, errors are automatically downgraded to a STATUS_DECLINE response.

CONFIGURATION OPTIONS

The following list details the configuration options that
can be provided to the Template::Filters new() construc
tor.

FILTERS: The FILTERS option can be used to specify custom fil
ters which can then be used with the FILTER directive
like any other. These are added to the standard fil
ters which are available by default. Filters speci
fied via this option will mask any standard filters of
the same name.; 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 refer
ence and a flag which indicates if the filter is
static (0) or dynamic (1). A filter may also be spec
ified as a solitary subroutine reference and is
assumed to be static.

$filters = Template::Filters->new({
FILTERS => {
'sfilt1' => static_filter, # static
'sfilt2' => [ static_filter, 0 ], # same

as above
'dfilt1' => [ dyanamic_filter_factory, 1

],

},

});; Additional filters can be specified at any time by
calling the define_filter() method on the current Tem plate::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.

my $context = $template->context();
$context->define_filter('new_html', new_html);
$context->define_filter('new_repeat', new_repeat,

1);; 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 stati
cally. The subroutine reference is simply returned
when that particular filter is requested. The subrou
tine is called to filter the output of a template
block which is passed as the only argument. The sub
routine should return the modified text.

sub static_filter {
my $text = shift;
# do something to modify $text...
return $text;

}; The following template fragment:

[% FILTER sfilt1 %]
Blah blah blah.
[% END %]; is approximately equivalent to:

&static_filter("0lah blah blah.0);; 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 Tem
plate::Context object is passed as the first parame
ter, followed by any additional parameters specified.
The subroutine should return another subroutine refer
ence (usually a closure) which implements the filter.

sub dynamic_filter_factory {
my ($context, @args) = @_;

return sub {
my $text = shift;
# do something to modify $text...
return $text;

}

}; The following template fragment:

[% FILTER dfilt1(123, 456) %]
Blah blah blah
[% END %]; is approximately equivalent to:

my $filter = &dynamic_filter_factory($context,

123, 456);
&$filter("0lah blah blah.0);; See the FILTER directive for further examples.
TOLERANT: The TOLERANT flag is used by the various Template
Toolkit provider modules (Template::Provider, Tem
plate::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 TOLER
ANT 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 toler
ated failure or a genuine disinclination to comply,
then a '<resource> not found' exception is raised.

TEMPLATE TOOLKIT FILTERS

The following standard filters are distributed with the
Template Toolkit.

format(format)

The 'format' filter takes a format string as a parameter (as per printf()) and formats each line of text accord ingly.: [% FILTER format('') %]
This is a block of text filtered
through the above format.
[% END %]
output::
upper
Folds the input to UPPER CASE.: [% "hello world" FILTER upper %]
output:: HELLO WORLD
lower
Folds the input to lower case.: [% "Hello World" FILTER lower %]
output:: hello world
ucfirst
Folds the first character of the input to UPPER CASE.: [% "hello" FILTER ucfirst %]
output:: Hello
lcfirst
Folds the first character of the input to lower case.: [% "HELLO" FILTER lcfirst %]
output:: hELLO
trim
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 configu ration option.: [% INCLUDE myfile | trim %]
collapse
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.: [% FILTER collapse %]

The cat

sat on

the mat; [% END %]
output:: The cat sat on the mat
html
Converts the characters '<', '>' and '&' to '<', '>' and '&', respectively, protecting them from being interpreted as representing HTML tags or entities.: [% FILTER html %]
Binary "<=>" returns -1, 0, or 1 depending on...
[% END %]
output:: Binary "<=>" returns -1, 0, or 1 depending on...
html_entity
The html filter is fast and simple but it doesn't encode
the full range of HTML entities that your text may con
tain. 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 'é'). If neither module
is available on your system then an 'html_all' exception
will be thrown reporting an appropriate message.
For further information on HTML entity encoding, see http://www.w3.org/TR/REC-html40/sgml/entities.html.
html_para
This filter formats a block of text into HTML paragraphs. A sequence of two or more newlines is used as the delim iter for paragraphs which are then wrapped in HTML ... tags.: [% FILTER html_para %]
The cat sat on the mat.; Mary had a little lamb.
[% END %]
output:: 
The cat sat on the mat.
; 
Mary had a little lamb.
html_break
Similar to the html_para filter described above, but uses the HTML tag sequence to join paragraphs.: [% FILTER html_break %]
The cat sat on the mat.; Mary had a little lamb.
[% END %]
output:: The cat sat on the mat.
 
 
Mary had a little lamb.
uri
This filter URI escapes the input text, converting any characters outside of the permitted URI character set (as defined by RFC 2396) into a %nn hex escape.: [% 'my file.html' | uri %]
output:: my%20file.html
Note that URI escaping isn't always enough when generating hyperlinks in an HTML document. The "&" 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.: <a href="[% filename | uri | html %]">click here</a>
indent(pad)
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.: [% FILTER indent('ME> ') %]
blah blah blah
cabbages, rhubard, onions
[% END %]
output:: ME> blah blah blah
ME> cabbages, rhubard, onions
truncate(length)
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).: [% FILTER truncate(21) %]
I have much to say on this matter that has previously
been said on more than one occasion.
[% END %]
output:: I have much to say...
repeat(iterations)
Repeats the text block for as many iterations as are spec ified (default: 1).: [% FILTER repeat(3) %]
We want more beer and we want more beer,
[% END %]
We are the more beer wanters!
output:: 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!
remove(string)
Searches the input text for any occurrences of the speci fied string and removes them. A Perl regular expression may be specified as the search string.: [% "The cat sat on the mat" FILTER remove(' %]
output:: Thecatsatonthemat
replace(search, replace)
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.: [% "The cat sat on the mat" | replace(' '_') %]
output:: The_cat_sat_on_the_mat
redirect(file)
The 'redirect' filter redirects the output of the block into a separate file, specified relative to the OUT PUT_PATH configuration item.: [% FOREACH user = myorg.userlist %]
[% FILTER redirect("users/${user.id}.html") %]
[% INCLUDE userinfo %]

[% END %]; [% END %]
or more succinctly, using side-effect notation:: [% INCLUDE userinfo
FILTER redirect("users/${user.id}.html")
FOREACH user = myorg.userlist

%]; A 'file' exception will be thrown if the OUTPUT_PATH
option is undefined.; eval(template_text); 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 frag
ments from an external source such as a database, which
can then be processed in the template as required.

my $vars = {
fragment => "The cat sat on the [% place %]",

};
$template->process($file, $vars);; The following example:

[% fragment | eval %]; is therefore equivalent to

The cat sat on the [% place %]; The 'evaltt' filter is provided as an alias for 'eval'.; perl(perlcode); 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.

[% my_perl_code | perl %]; In most cases, the [% PERL %] ... [% END %] 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:

[% PERL %]
[% my_perl_code %]
[% END %]; as well as

[% FILTER perl %]
[% my_perl_code %]
[% END %]; The 'evalperl' filter is provided as an alias for 'perl'
for backwards compatibility.; stdout(binmode); 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.; 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.; stderr; The stderr filter prints the output generated by the
enclosing block to STDERR.; null; The null filter prints nothing. This is useful for plug
ins 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:

[% 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;; -%]
Notice the use of the stdout filter to ensure that a par ticular expression generates output to stdout (in this case in binary mode).
latex(outputType)
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".
The text block should be a complete LaTeX source file.: g
i% FILTER latex("pdf") -%]
ncumentclass{article}
{
dnt}
o
itle{A Sample TT2 eX Source File}
uthor{Craig Barratt}
ketitle; tion{Introduction}
This is some text.; 0{document}
[% END -%]
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 '-%]' for the END_TAG to remove the trail ing new line.
One example where you might prepend text is in a CGI script where you might include the Content-Type before the latex output, eg:: gontent-Type: application/pdf
i
n% FILTER latex("pdf") -%]
{cumentclass{article}
dnt}
...
0{document}
[% END -%]
m
In other cases you might use the redirect filter to put the output into a file, rather than delivering it to std out.g This might be suitable for batch scripts:: i
n% output = FILTER latex("pdf") -%]
{cumentclass{article}
dnt}
...
0{document}
[% END; output | redirect("document.pdf", 1) -%]
m
(Notice the second argument to redirect to force binary mode.)
Note that the latex filter runs one or two external pro grams, so it isn't very fast. But for modest documents the performance is adequate, even for interactive applica tions.
A error of type 'latex' will be thrown if there is an error reported by latex, pdflatex or dvips.

AUTHOR

Andy Wardley <abw@andywardley.com>

<http://www.andywardley.com/|http://www.andywardley.com/>

VERSION

2.58, distributed as part of the Template Toolkit version
2.08, released on 30 July 2002.

COPYRIGHT

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

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