Template::Plugins(3)

NAME
Template::Plugins - Plugin provider module

SYNOPSIS
    use Template::Plugins;
    $plugin_provider = Template::Plugins->new(\%options);
    ($plugin, $error) = $plugin_provider->fetch($name, @args);

DESCRIPTION
The Template::Plugins module defines a provider class which can be used to load and instantiate Template Toolkit plugin modules.

METHODS

  new(\%params)
Constructor method which instantiates and returns a reference to a Template::Plugins object. A reference to a hash array of configuration items may be passed as a parameter. These are described below.

Note that the Template.pm front-end module creates a Template::Plugins provider, passing all configuration items. Thus, the examples shown below in the form:

    $plugprov = Template::Plugins->new({
        PLUGIN_BASE => 'MyTemplate::Plugin',
        LOAD_PERL   => 1,
        ...
    });
can also be used via the Template module as:

    $ttengine = Template->new({
        PLUGIN_BASE => 'MyTemplate::Plugin',
        LOAD_PERL   => 1,
        ...
    });
as well as the more explicit form of:

    $plugprov = Template::Plugins->new({
        PLUGIN_BASE => 'MyTemplate::Plugin',
        LOAD_PERL   => 1,
        ...
    });
    $ttengine = Template->new({
        LOAD_PLUGINS => [ $plugprov ],
    });

  fetch($name, @args)
Called to request that a plugin of a given name be provided. The relevant module is first loaded (if necessary) and the load() class method called to return the factory class name (usually the same package name) or a factory object (a prototype). The new() method is then called as a class or object method against the factory, passing all remaining parameters.

Returns a reference to a new plugin object or ($error, STATUS_ERROR) on error. May also return (undef, STATUS_DECLINED) to decline to serve the request. If TOLERANT is set then all errors will be returned as declines.

CONFIGURATION OPTIONS
The following list details the configuration options that can be provided to the Template::Plugins new() constructor.

PLUGINS
    The PLUGINS options can be used to provide a reference to a hash array that maps plugin names to Perl module names. A number of standard plugins are defined (e.g. 'table', 'cgi', 'dbi', etc.) which map to their corresponding Template::Plugin::* counterparts. These can be redefined by values in the PLUGINS hash.

        my $plugins = Template::Plugins->new({
            PLUGINS => {
                cgi => 'MyOrg::Template::Plugin::CGI',
                foo => 'MyOrg::Template::Plugin::Foo',
                bar => 'MyOrg::Template::Plugin::Bar',
            },
        });
    The USE directive is used to create plugin objects and does so by calling the plugin() method on the current Template::Context object. If the plugin name is defined in the PLUGINS hash then the corresponding Perl module is loaded via require(). The context then calls the load() class method which should return the class name (default and general case) or a prototype object against which the new() method can be called to instantiate individual plugin objects.

    If the plugin name is not defined in the PLUGINS hash then the PLUGIN_BASE and/or LOAD_PERL options come into effect.

PLUGIN_BASE
    If a plugin is not defined in the PLUGINS hash then the PLUGIN_BASE is used to attempt to construct a correct Perl module name which can be successfully loaded.

    The PLUGIN_BASE can be specified as a single value or as a reference to an array of multiple values. The default PLUGIN_BASE value, 'Template::Plugin', is always added the the end of the PLUGIN_BASE list (a single value is first converted to a list). Each value should contain a Perl package name to which the requested plugin name is appended.

    example 1:

        my $plugins = Template::Plugins->new({
            PLUGIN_BASE => 'MyOrg::Template::Plugin',
        });
        [% USE Foo %]    # => MyOrg::Template::Plugin::Foo
                           or        Template::Plugin::Foo
    example 2:

        my $plugins = Template::Plugins->new({
            PLUGIN_BASE => [   'MyOrg::Template::Plugin',
                             'YourOrg::Template::Plugin'  ],
        });
        [% USE Foo %]    # =>   MyOrg::Template::Plugin::Foo
                           or YourOrg::Template::Plugin::Foo
                           or          Template::Plugin::Foo

LOAD_PERL
    If a plugin cannot be loaded using the PLUGINS or PLUGIN_BASE approaches then the provider can make a final attempt to load the module without prepending any prefix to the module path. This allows regular Perl modules (i.e. those that don't reside in the Template::Plugin or some other such namespace) to be loaded and used as plugins.

    By default, the LOAD_PERL option is set to 0 and no attempt will be made to load any Perl modules that aren't named explicitly in the PLUGINS hash or reside in a package as named by one of the PLUGIN_BASE components.

    Plugins loaded using the PLUGINS or PLUGIN_BASE receive a reference to the current context object as the first argument to the new() constructor. Modules loaded using LOAD_PERL are assumed to not conform to the plugin interface. They must provide a new() class method for instantiating objects but it will not receive a reference to the context as the first argument. Plugin modules should provide a load() class method (or inherit the default one from the Template::Plugin base class) which is called the first time the plugin is loaded. Regular Perl modules need not. In all other respects, regular Perl objects and Template Toolkit plugins are identical.

    If a particular Perl module does not conform to the common, but not unilateral, new() constructor convention then a simple plugin wrapper can be written to interface to it.

TOLERANT
    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.

TEMPLATE TOOLKIT PLUGINS
The following plugin modules are distributed with the Template Toolkit. Some of the plugins interface to external modules (detailed below) which should be downloaded from any CPAN site and installed before using the plugin.

  Autoformat
The Autoformat plugin is an interface to Damian Conway's Text::Autoformat Perl module which provides advanced text wrapping and formatting. See the Template::Plugin::Autoformat manpage and the Text::Autoformat manpage for further details.

    [% USE autoformat(left=10, right=20) %]
    [% autoformat(mytext) %]        # call autoformat sub
    [% mytext FILTER autoformat %]  # or use autoformat filter
The Text::Autoformat module is available from CPAN:

    http://www.cpan.org/modules/by-module/Text/

  CGI
The CGI plugin is a wrapper around Lincoln Stein's <lstein@genome.wi.mit.edu> CGI.pm module. The plugin is distributed with the Template Toolkit (see the Template::Plugin::CGI manpage) and the CGI module itself is distributed with recent versions Perl, or is available from CPAN.

    [% USE CGI %]
    [% CGI.param('param_name') %]
    [% CGI.start_form %]
    [% CGI.popup_menu( Name   => 'color',
                       Values => [ 'Green', 'Brown' ] ) %]
    [% CGI.end_form %]

  Datafile
Provides an interface to data stored in a plain text file in a simple delimited format. The first line in the file specifies field names which should be delimiter by any non-word character sequence. Subsequent lines define data using the same delimiter as int he first line. Blank lines and comments (lines starting '#') are ignored. See the Template::Plugin::Datafile manpage for further details.

/tmp/mydata:

    # define names for each field
    id : email : name : tel
    # here's the data
    fred : fred@here.com : Fred Smith : 555-1234
    bill : bill@here.com : Bill White : 555-5678
example:

    [% USE userlist = datafile('/tmp/mydata') %]
    [% FOREACH user = userlist %]
       [% user.name %] ([% user.id %])
    [% END %]

  Date
The Date plugin provides an easy way to generate formatted time and date strings by delegating to the POSIX strftime() routine. See the Template::Plugin::Date manpage and the POSIX manpage for further details.

    [% USE date %]
    [% date.format %]           # current time/date
    File last modified: [% date.format(template.modtime) %]

  Directory
The Directory plugin provides a simple interface to a directory and the files within it. See the Template::Plugin::Directory manpage for further details.

    [% USE dir = Directory('/tmp') %]
    [% FOREACH file = dir.files %]
        # all the plain files in the directory
    [% END %]
    [% FOREACH file = dir.dirs %]
        # all the sub-directories
    [% END %]

  DBI
The DBI plugin, developed by Simon Matthews <sam@knowledgepool.com>, brings the full power of Tim Bunce's <Tim.Bunce@ig.co.uk> database interface module (DBI) to your templates. See the Template::Plugin::DBI manpage and the DBI manpage for further details.

    [% USE DBI('dbi:driver:database', 'user', 'pass') %]
    [% FOREACH user = DBI.query( 'SELECT * FROM users' ) %]
       [% user.id %] [% user.name %]
    [% END %]
The DBI and relevant DBD modules are available from CPAN:

  http://www.cpan.org/modules/by-module/DBI/

  Dumper
The Dumper plugin provides an interface to the Data::Dumper module. See the Template::Plugin::Dumper manpage and the Data::Dumper manpage for futher details.

    [% USE dumper(indent=0, pad="<br>") %]
    [% dumper.dump(myvar, yourvar) %]

  File
The File plugin provides a general abstraction for files and can be used to fetch information about specific files within a filesystem. See the Template::Plugin::File manpage for further details.

    [% USE File('/tmp/foo.html') %]
    [% File.name %]     # foo.html
    [% File.dir %]      # /tmp
    [% File.mtime %]    # modification time

  Filter
This module implements a base class plugin which can be subclassed to easily create your own modules that define and install new filters.

    package MyOrg::Template::Plugin::MyFilter;
    use Template::Plugin::Filter;
    use base qw( Template::Plugin::Filter );
    sub filter {
        my ($self, $text) = @_;
        # ...mungify $text...
        return $text;
    }
    # now load it...
    [% USE MyFilter %]
    # ...and use the returned object as a filter
    [% FILTER $MyFilter %]
      ...
    [% END %]
See the Template::Plugin::Filter manpage for further details.

  Format
The Format plugin provides a simple way to format text according to a printf()-like format. See the Template::Plugin::Format manpage for further details.

    [% USE bold = format('<b>%s</b>') %]
    [% bold('Hello') %]

  GD::Image, GD::Polygon, GD::Constants
These plugins provide access to the GD graphics library via Lincoln D. Stein's GD.pm interface. These plugins allow PNG, JPEG and other graphical formats to be generated.

    [% FILTER null;
        USE im = GD.Image(100,100);
        # allocate some colors
        black = im.colorAllocate(0,   0, 0);
        red   = im.colorAllocate(255,0,  0);
        blue  = im.colorAllocate(0,  0,  255);
        # Draw a blue oval
        im.arc(50,50,95,75,0,360,blue);
        # And fill it with red
        im.fill(50,50,red);
        # Output image in PNG format
        im.png | stdout(1);
       END;
    -%]
See the Template::Plugin::GD::Image manpage for further details.

  GD::Text, GD::Text::Align, GD::Text::Wrap
These plugins provide access to Martien Verbruggen's GD::Text, GD::Text::Align and GD::Text::Wrap modules. These plugins allow the layout, alignment and wrapping of text when drawing text in GD images.

    [% FILTER null;
        USE gd  = GD.Image(200,400);
        USE gdc = GD.Constants;
        black = gd.colorAllocate(0,   0, 0);
        green = gd.colorAllocate(0, 255, 0);
        txt = "This is some long text. " | repeat(10);
        USE wrapbox = GD.Text.Wrap(gd,
         line_space  => 4,
         color       => green,
         text        => txt,
        );
        wrapbox.set_font(gdc.gdMediumBoldFont);
        wrapbox.set(align => 'center', width => 160);
        wrapbox.draw(20, 20);
        gd.png | stdout(1);
      END;
    -%]
See the Template::Plugin::GD::Text manpage, the Template::Plugin::GD::Text::Align manpage and the Template::Plugin::GD::Text::Wrap manpage for further details.

  GD::Graph::lines, GD::Graph::bars, GD::Graph::points, GD::Graph::linespoin ts, GD::Graph::area, GD::Graph::mixed, GD::Graph::pie
These plugins provide access to Martien Verbruggen's GD::Graph module that allows graphs, plots and charts to be created. These plugins allow graphs, plots and charts to be generated in PNG, JPEG and other graphical formats.

    [% FILTER null;
        data = [
            ["1st","2nd","3rd","4th","5th","6th"],
            [    4,    2,    3,    4,    3,  3.5]
        ];
        USE my_graph = GD.Graph.pie(250, 200);
        my_graph.set(
                title => 'A Pie Chart',
                label => 'Label',
                axislabelclr => 'black',
                pie_height => 36,
                transparent => 0,
        );
        my_graph.plot(data).png | stdout(1);
      END;
    -%]
See the Template::Plugin::GD::Graph::lines manpage, the Template::Plugin::GD::Graph::bars manpage, the Template::Plugin::GD::Graph::points manpage, the Template::Plugin::GD::Graph::linespoints manpage, the Template::Plugin::GD::Graph::area manpage, the Template::Plugin::GD::Graph::mixed manpage, the Template::Plugin::GD::Graph::pie manpage, and the GD::Graph manpage, for more details.

  GD::Graph::bars3d, GD::Graph::lines3d, GD::Graph::pie3d
These plugins provide access to Jeremy Wadsack's GD::Graph3d module. This allows 3D bar charts and 3D lines plots to be generated.

    [% FILTER null;
        data = [
            ["1st","2nd","3rd","4th","5th","6th","7th", "8th", "9th"],
            [    1,    2,    5,    6,    3,  1.5,    1,     3,     4],
        ];
        USE my_graph = GD.Graph.bars3d();
        my_graph.set(
            x_label         => 'X Label',
            y_label         => 'Y label',
            title           => 'A 3d Bar Chart',
            y_max_value     => 8,
            y_tick_number   => 8,
            y_label_skip    => 2,
            # shadows
            bar_spacing     => 8,
            shadow_depth    => 4,
            shadowclr       => 'dred',
            transparent     => 0,
        my_graph.plot(data).png | stdout(1);
      END;
    -%]
See the Template::Plugin::GD::Graph::lines3d manpage, the Template::Plugin::GD::Graph::bars3d manpage, and the Template::Plugin::GD::Graph::pie3d manpage for more details.

  HTML
The HTML plugin is very new and very basic, implementing a few useful methods for generating HTML. It is likely to be extended in the future or integrated with a larger project to generate HTML elements in a generic way (as discussed recently on the mod_perl mailing list).

    [% USE HTML %]
    [% HTML.escape("if (a < b && c > d) ..." %]
    [% HTML.attributes(border => 1, cellpadding => 2) %]
    [% HTML.element(table => { border => 1, cellpadding => 2 }) %]
See the Template::Plugin::Iterator manpage for further details.

  Iterator
The Iterator plugin provides a way to create a Template::Iterator object to iterate over a data set. An iterator is created automatically by the FOREACH directive and is aliased to the 'loop' variable. This plugin allows an iterator to be explicitly created with a given name, or the default plugin name, 'iterator'. See the Template::Plugin::Iterator manpage for further details.

    [% USE iterator(list, args) %]
    [% FOREACH item = iterator %]
       [% '<ul>' IF iterator.first %]
       <li>[% item %]
       [% '</ul>' IF iterator.last %]
    [% END %]

  Pod
This plugin provides an interface to the Pod::POD module which parses POD documents into an internal object model which can then be traversed and presented through the Template Toolkit.

    [% USE Pod(podfile) %]
    [% FOREACH head1 = Pod.head1;
         FOREACH head2 = head1/head2;
           ...
         END;
       END
    %]

  String
The String plugin implements an object-oriented interface for manipulating strings. See the Template::Plugin::String manpage for further details.

    [% USE String 'Hello' %]
    [% String.append(' World') %]
    [% msg = String.new('Another string') %]
    [% msg.replace('string', 'text') %]
    The string "[% msg %]" is [% msg.length %] characters long.

  Table
The Table plugin allows you to format a list of data items into a virtual table by specifying a fixed number of rows or columns, with an optional overlap. See the Template::Plugin::Table manpage for further details.

    [% USE table(list, rows=10, overlap=1) %]
    [% FOREACH item = table.col(3) %]
       [% item %]
    [% END %]

  URL
The URL plugin provides a simple way of contructing URLs from a base part and a variable set of parameters. See the Template::Plugin::URL manpage for further details.

    [% USE mycgi = url('/cgi-bin/bar.pl', debug=1) %]
    [% mycgi %]
       # ==> /cgi/bin/bar.pl?debug=1
    [% mycgi(mode='submit') %]
       # ==> /cgi/bin/bar.pl?mode=submit&debug=1

  Wrap
The Wrap plugin uses the Text::Wrap module by David Muir Sharnoff <muir@idiom.com> (with help from Tim Pierce and many many others) to provide simple paragraph formatting. See the Template::Plugin::Wrap manpage and the Text::Wrap manpage for further details.

    [% USE wrap %]
    [% wrap(mytext, 40, '* ', '  ') %]  # use wrap sub
    [% mytext FILTER wrap(40) -%]       # or wrap FILTER
The Text::Wrap module is available from CPAN:

    http://www.cpan.org/modules/by-module/Text/

  XML::DOM
The XML::DOM plugin gives access to the XML Document Object Module via Clark Cooper <cooper@sch.ge.com> and Enno Derksen's <enno@att.com> XML::DOM module. See the Template::Plugin::XML::DOM manpage and the XML::DOM manpage for further details.

    [% USE dom = XML.DOM %]
    [% doc = dom.parse(filename) %]
    [% FOREACH node = doc.getElementsByTagName('CODEBASE') %]
       * [% node.getAttribute('href') %]
    [% END %]
The plugin requires the XML::DOM module, available from CPAN:

    http://www.cpan.org/modules/by-module/XML/

  XML::RSS
The XML::RSS plugin is a simple interface to Jonathan Eisenzopf's <eisen@pobox.com> XML::RSS module. A RSS (Rich Site Summary) file is typically used to store short news 'headlines' describing different links within a site. This plugin allows you to parse RSS files and format the contents accordingly using templates. See the Template::Plugin::XML::RSS manpage and the XML::RSS manpage for further details.

    [% USE news = XML.RSS(filename) %]
    [% FOREACH item = news.items %]
       <a href="[% item.link %]">[% item.title %]</a>
    [% END %]
The XML::RSS module is available from CPAN:

    http://www.cpan.org/modules/by-module/XML/

  XML::Simple
This plugin implements an interface to the XML::Simple module.

    [% USE xml = XML.Simple(xml_file_or_text) %]
    [% xml.head.title %]
See the Template::Plugin::XML::Simple manpage for further details.

  XML::Style
This plugin defines a filter for performing simple stylesheet based transformations of XML text.

    [% USE xmlstyle
           table = {
               attributes = {
                   border      = 0
                   cellpadding = 4
                   cellspacing = 1
               }
           }
    %]
    [% FILTER xmlstyle %]
    <table>
    <tr>
      <td>Foo</td> <td>Bar</td> <td>Baz</td>
    </tr>
    </table>
    [% END %]
See the Template::Plugin::XML::Style manpage for further details.

  XML::XPath
The XML::XPath plugin provides an interface to Matt Sergeant's <matt@sergeant.org> XML::XPath module. See the Template::Plugin::XML::XPath manpage and the XML::XPath manpage for further details.

    [% USE xpath = XML.XPath(xmlfile) %]
    [% FOREACH page = xpath.findnodes('/html/body/page') %]
       [% page.getAttribute('title') %]
    [% END %]
The plugin requires the XML::XPath module, available from CPAN:

    http://www.cpan.org/modules/by-module/XML/

BUGS / ISSUES

•   It might be worthwhile being able to distinguish between absolute module names and those which should be applied relative to PLUGIN_BASE directories. For example, use 'MyNamespace::MyModule' to denote absolute module names (e.g. LOAD_PERL), and 'MyNamespace.MyModule' to denote relative to PLUGIN_BASE.

AUTHOR
Andy Wardley <abw@andywardley.com>

http://www.andywardley.com/

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

COPYRIGHT
  Copyright (C) 1996-2002 Andy Wardley.  All Rights Reserved.
  Copyright (C) 1998-2002 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.

SEE ALSO
Template, Template::Plugin, Template::Context