File: //usr/local/ssl/local/share/man/man3/Template::Plugin::Filter.3
.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sh \" Subsection heading
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
.PP
..
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" Set up some character translations and predefined strings. \*(-- will
.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left
.\" double quote, and \*(R" will give a right double quote. | will give a
.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to
.\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C'
.\" expand to `' in nroff, nothing in troff, for use with C<>.
.tr \(*W-|\(bv\*(Tr
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
.ie n \{\
. ds -- \(*W-
. ds PI pi
. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
. ds L" ""
. ds R" ""
. ds C` ""
. ds C' ""
'br\}
.el\{\
. ds -- \|\(em\|
. ds PI \(*p
. ds L" ``
. ds R" ''
'br\}
.\"
.\" If the F register is turned on, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. nr % 0
. rr F
.\}
.\"
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.hy 0
.if n .na
.\"
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
.\" Fear. Run. Save yourself. No user-serviceable parts.
. \" fudge factors for nroff and troff
.if n \{\
. ds #H 0
. ds #V .8m
. ds #F .3m
. ds #[ \f1
. ds #] \fP
.\}
.if t \{\
. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
. ds #V .6m
. ds #F 0
. ds #[ \&
. ds #] \&
.\}
. \" simple accents for nroff and troff
.if n \{\
. ds ' \&
. ds ` \&
. ds ^ \&
. ds , \&
. ds ~ ~
. ds /
.\}
.if t \{\
. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
.\}
. \" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
.ds 8 \h'\*(#H'\(*b\h'-\*(#H'
.ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#]
.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
. \" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
. \" for low resolution devices (crt and lpr)
.if \n(.H>23 .if \n(.V>19 \
\{\
. ds : e
. ds 8 ss
. ds o a
. ds d- d\h'-1'\(ga
. ds D- D\h'-1'\(hy
. ds th \o'bp'
. ds Th \o'LP'
. ds ae ae
. ds Ae AE
.\}
.rm #[ #] #H #V #F C
.\" ========================================================================
.\"
.IX Title "Template::Plugin::Filter 3"
.TH Template::Plugin::Filter 3 "2012-01-24" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
Template::Plugin::Filter \- Base class for plugin filters
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& package MyOrg::Template::Plugin::MyFilter;
.Ve
.PP
.Vb 2
\& use Template::Plugin::Filter;
\& use base qw( Template::Plugin::Filter );
.Ve
.PP
.Vb 2
\& sub filter {
\& my ($self, $text) = @_;
.Ve
.PP
.Vb 1
\& # ...mungify $text...
.Ve
.PP
.Vb 2
\& return $text;
\& }
.Ve
.PP
.Vb 2
\& # now load it...
\& [% USE MyFilter %]
.Ve
.PP
.Vb 4
\& # ...and use the returned object as a filter
\& [% FILTER $MyFilter %]
\& ...
\& [% END %]
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
This module implements a base class for plugin filters. It hides
the underlying complexity involved in creating and using filters
that get defined and made available by loading a plugin.
.PP
To use the module, simply create your own plugin module that is
inherited from the \f(CW\*(C`Template::Plugin::Filter\*(C'\fR class.
.PP
.Vb 1
\& package MyOrg::Template::Plugin::MyFilter;
.Ve
.PP
.Vb 2
\& use Template::Plugin::Filter;
\& use base qw( Template::Plugin::Filter );
.Ve
.PP
Then simply define your \f(CW\*(C`filter()\*(C'\fR method. When called, you get
passed a reference to your plugin object (\f(CW$self\fR) and the text
to be filtered.
.PP
.Vb 2
\& sub filter {
\& my ($self, $text) = @_;
.Ve
.PP
.Vb 1
\& # ...mungify $text...
.Ve
.PP
.Vb 2
\& return $text;
\& }
.Ve
.PP
To use your custom plugin, you have to make sure that the Template
Toolkit knows about your plugin namespace.
.PP
.Vb 3
\& my $tt2 = Template->new({
\& PLUGIN_BASE => 'MyOrg::Template::Plugin',
\& });
.Ve
.PP
Or for individual plugins you can do it like this:
.PP
.Vb 5
\& my $tt2 = Template->new({
\& PLUGINS => {
\& MyFilter => 'MyOrg::Template::Plugin::MyFilter',
\& },
\& });
.Ve
.PP
Then you \f(CW\*(C`USE\*(C'\fR your plugin in the normal way.
.PP
.Vb 1
\& [% USE MyFilter %]
.Ve
.PP
The object returned is stored in the variable of the same name,
\&'\f(CW\*(C`MyFilter\*(C'\fR'. When you come to use it as a \f(CW\*(C`FILTER\*(C'\fR, you should add
a dollar prefix. This indicates that you want to use the filter
stored in the variable '\f(CW\*(C`MyFilter\*(C'\fR' rather than the filter named
\&'\f(CW\*(C`MyFilter\*(C'\fR', which is an entirely different thing (see later for
information on defining filters by name).
.PP
.Vb 3
\& [% FILTER $MyFilter %]
\& ...text to be filtered...
\& [% END %]
.Ve
.PP
You can, of course, assign it to a different variable.
.PP
.Vb 1
\& [% USE blat = MyFilter %]
.Ve
.PP
.Vb 3
\& [% FILTER $blat %]
\& ...text to be filtered...
\& [% END %]
.Ve
.PP
Any configuration parameters passed to the plugin constructor from the
\&\f(CW\*(C`USE\*(C'\fR directive are stored internally in the object for inspection by
the \f(CW\*(C`filter()\*(C'\fR method (or indeed any other method). Positional
arguments are stored as a reference to a list in the \f(CW\*(C`_ARGS\*(C'\fR item while
named configuration parameters are stored as a reference to a hash
array in the \f(CW\*(C`_CONFIG\*(C'\fR item.
.PP
For example, loading a plugin as shown here:
.PP
.Vb 1
\& [% USE blat = MyFilter 'foo' 'bar' baz = 'blam' %]
.Ve
.PP
would allow the \f(CW\*(C`filter()\*(C'\fR method to do something like this:
.PP
.Vb 2
\& sub filter {
\& my ($self, $text) = @_;
.Ve
.PP
.Vb 2
\& my $args = $self->{ _ARGS }; # [ 'foo', 'bar' ]
\& my $conf = $self->{ _CONFIG }; # { baz => 'blam' }
.Ve
.PP
.Vb 1
\& # ...munge $text...
.Ve
.PP
.Vb 2
\& return $text;
\& }
.Ve
.PP
By default, plugins derived from this module will create static
filters. A static filter is created once when the plugin gets
loaded via the \f(CW\*(C`USE\*(C'\fR directive and re-used for all subsequent
\&\f(CW\*(C`FILTER\*(C'\fR operations. That means that any argument specified with
the \f(CW\*(C`FILTER\*(C'\fR directive are ignored.
.PP
Dynamic filters, on the other hand, are re-created each time
they are used by a \f(CW\*(C`FILTER\*(C'\fR directive. This allows them to act
on any parameters passed from the \f(CW\*(C`FILTER\*(C'\fR directive and modify
their behaviour accordingly.
.PP
There are two ways to create a dynamic filter. The first is to
define a \f(CW$DYNAMIC\fR class variable set to a true value.
.PP
.Vb 3
\& package MyOrg::Template::Plugin::MyFilter;
\& use base 'Template::Plugin::Filter';
\& our $DYNAMIC = 1;
.Ve
.PP
The other way is to set the internal \f(CW\*(C`_DYNAMIC\*(C'\fR value within the \f(CW\*(C`init()\*(C'\fR
method which gets called by the \f(CW\*(C`new()\*(C'\fR constructor.
.PP
.Vb 5
\& sub init {
\& my $self = shift;
\& $self->{ _DYNAMIC } = 1;
\& return $self;
\& }
.Ve
.PP
When this is set to a true value, the plugin will automatically
create a dynamic filter. The outcome is that the \f(CW\*(C`filter()\*(C'\fR method
will now also get passed a reference to an array of postional
arguments and a reference to a hash array of named parameters.
.PP
So, using a plugin filter like this:
.PP
.Vb 1
\& [% FILTER $blat 'foo' 'bar' baz = 'blam' %]
.Ve
.PP
would allow the \f(CW\*(C`filter()\*(C'\fR method to work like this:
.PP
.Vb 2
\& sub filter {
\& my ($self, $text, $args, $conf) = @_;
.Ve
.PP
.Vb 3
\& # $args = [ 'foo', 'bar' ]
\& # $conf = { baz => 'blam' }
\& }
.Ve
.PP
In this case can pass parameters to both the \s-1USE\s0 and \s-1FILTER\s0 directives,
so your \fIfilter()\fR method should probably take that into account.
.PP
.Vb 1
\& [% USE MyFilter 'foo' wiz => 'waz' %]
.Ve
.PP
.Vb 3
\& [% FILTER $MyFilter 'bar' biz => 'baz' %]
\& ...
\& [% END %]
.Ve
.PP
You can use the \f(CW\*(C`merge_args()\*(C'\fR and \f(CW\*(C`merge_config()\*(C'\fR methods to do a quick
and easy job of merging the local (e.g. \f(CW\*(C`FILTER\*(C'\fR) parameters with the
internal (e.g. \f(CW\*(C`USE\*(C'\fR) values and returning new sets of conglomerated
data.
.PP
.Vb 2
\& sub filter {
\& my ($self, $text, $args, $conf) = @_;
.Ve
.PP
.Vb 2
\& $args = $self->merge_args($args);
\& $conf = $self->merge_config($conf);
.Ve
.PP
.Vb 4
\& # $args = [ 'foo', 'bar' ]
\& # $conf = { wiz => 'waz', biz => 'baz' }
\& ...
\& }
.Ve
.PP
You can also have your plugin install itself as a named filter by
calling the \f(CW\*(C`install_filter()\*(C'\fR method from the \f(CW\*(C`init()\*(C'\fR method. You
should provide a name for the filter, something that you might
like to make a configuration option.
.PP
.Vb 6
\& sub init {
\& my $self = shift;
\& my $name = $self->{ _CONFIG }->{ name } || 'myfilter';
\& $self->install_filter($name);
\& return $self;
\& }
.Ve
.PP
This allows the plugin filter to be used as follows:
.PP
.Vb 1
\& [% USE MyFilter %]
.Ve
.PP
.Vb 3
\& [% FILTER myfilter %]
\& ...
\& [% END %]
.Ve
.PP
or
.PP
.Vb 1
\& [% USE MyFilter name = 'swipe' %]
.Ve
.PP
.Vb 3
\& [% FILTER swipe %]
\& ...
\& [% END %]
.Ve
.PP
Alternately, you can allow a filter name to be specified as the
first positional argument.
.PP
.Vb 6
\& sub init {
\& my $self = shift;
\& my $name = $self->{ _ARGS }->[0] || 'myfilter';
\& $self->install_filter($name);
\& return $self;
\& }
.Ve
.PP
.Vb 1
\& [% USE MyFilter 'swipe' %]
.Ve
.PP
.Vb 3
\& [% FILTER swipe %]
\& ...
\& [% END %]
.Ve
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Here's a complete example of a plugin filter module.
.PP
.Vb 3
\& package My::Template::Plugin::Change;
\& use Template::Plugin::Filter;
\& use base qw( Template::Plugin::Filter );
.Ve
.PP
.Vb 2
\& sub init {
\& my $self = shift;
.Ve
.PP
.Vb 1
\& $self->{ _DYNAMIC } = 1;
.Ve
.PP
.Vb 2
\& # first arg can specify filter name
\& $self->install_filter($self->{ _ARGS }->[0] || 'change');
.Ve
.PP
.Vb 2
\& return $self;
\& }
.Ve
.PP
.Vb 2
\& sub filter {
\& my ($self, $text, $args, $config) = @_;
.Ve
.PP
.Vb 2
\& $config = $self->merge_config($config);
\& my $regex = join('|', keys %$config);
.Ve
.PP
.Vb 1
\& $text =~ s/($regex)/$config->{ $1 }/ge;
.Ve
.PP
.Vb 2
\& return $text;
\& }
.Ve
.PP
.Vb 1
\& 1;
.Ve
.SH "AUTHOR"
.IX Header "AUTHOR"
Andy Wardley <abw@wardley.org> <http://wardley.org/>
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright (C) 1996\-2007 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::Plugin, Template::Filters, Template::Manual::Filters