path: root/README

NAME
    CGI::Application::Plugin::AnyTemplate - Use any templating system from
    within CGI::Application using a unified interface

VERSION
    Version 0.18

SYNOPSIS
    In your CGI::Application-based webapp:

        use base 'CGI::Application';
        use CGI::Application::Plugin::AnyTemplate;

        sub cgiapp_init {
            my $self = shift;

            # Set template options
            $self->template->config(
                default_type => 'TemplateToolkit',
            );
        }

    Later on, in a runmode:

        sub my_runmode {
            my $self = shift;

            my %template_params = (
                name     => 'Winston Churchill',
                age      => 7,
            );

            $self->template->fill('some_template', \%template_params);
        }

DESCRIPTION
  Template-Independence
    "CGI::Application::Plugin::AnyTemplate" allows you to use any supported
    Perl templating system using a single consistent interface.

    Currently supported templating systems include HTML::Template,
    HTML::Template::Expr, HTML::Template::Pluggable, Template::Toolkit and
    Petal.

    You can access any of these templating systems using the same interface.
    In this way, you can use the same code and switch templating systems on
    the fly.

    This approach has many uses. For instance, it can be useful in migrating
    your application from one templating system to another.

  Embedded Components
    In addition to template abstraction, "AnyTemplate" also provides a
    *embedded component mechanism*. For instance, you might include a
    *header* component at the top of every page and a *footer* component at
    the bottom of every page.

    These components are actually full CGI::Application run modes, and can
    do anything normal run mode can do, including processing form parameters
    and filling in their own templates. See below under "EMBEDDED
    COMPONENTS" for details.

  Multiple Named Template Configurations
    You can set up multiple named template configurations and select between
    them at run time.

        sub cgiapp_init {
            my $self = shift;

            # Can't use Template::Toolkit any more -
            # The boss wants everything has to be XML,
            # so we switch to Petal

            # Set old-style template options (legacy scripts)
            $self->template('oldstyle')->config(
                default_type => 'TemplateToolkit',
                TemplateToolkit => {
                    POST_CHOMP => 1,
                }
            );
            # Set new-style template options as default
            $self->template->config(
                default_type => 'Petal',
                auto_add_template_extension => 0,
            );
        }

        sub old_style_runmode {
            my $self = shift;

            # ...

            # use TemplateToolkit to fill template edit_user.tmpl
            $self->template('oldstyle')->fill('edit_user', \%params);

        }

        sub new_style_runmode {
            my $self = shift;

            # ...

            # use Petal to fill template edit_user.xhml
            $self->template->fill('edit_user.xhtml', \%params);

        }

  Flexible Syntax
    The syntax is pretty flexible. Pick a style that's most comfortable for
    you.

   CGI::Application::Plugin::TT style syntax
        $self->template->process('edit_user', \%params);

    or (with slightly less typing):

        $self->template->fill('edit_user', \%params);

   CGI::Application load_tmpl style syntax
        my $template = $self->template->load('edit_user');
        $template->param('foo' => 'bar');
        $template->output;

   Verbose syntax (for complete control)
        my $template = $self->template('named_config')->load(
            file              => 'edit_user'
            type              => 'TemplateToolkit'
            add_include_paths => '.',
        );

        $template->param('foo' => 'bar');
        $template->output;

    See also below under "CHANGING THE NAME OF THE 'template' METHOD".

METHODS
  config
    Initialize the "AnyTemplate" system and provide the default
    configuration.

        $self->template->config(
            default_type => 'HTMLTemplate',
        );

    You can keep multiple configurations handy at the same time by passing a
    value to "template":

        $self->template('oldstyle')->config(
            default_type => 'HTML::Template',
        );
        $self->template('newstyle')->config(
            default_type => 'HTML::Template::Expr',
        );

    Then in a runmode you can mix and match configurations:

        $self->template('oldstyle')->load  # loads an HTML::Template driver object
        $self->template('newstyle')->load  # loads an HTML::Template::Expr driver object

    The configuration passed to "config" is divided into three areas:
    *plugin configuration*, *driver configuration*, and *native
    configuration*:

        Config Type       What it Configures
        -----------       ------------------
        Plugin Config     AnyTemplate itself
        Driver Config     AnyTemplate Driver (e.g. HTMLTemplate)
        Native Config     Actual template module (e.g. HTML::Template)

    These are described in more detail below.

   Plugin Configuration
    These configuration params are specific to the
    "CGI::Application::Plugin::AnyTemplate" itself. They are included at the
    top level of the configuration hash passed to "config". For instance:

        $self->template->config(
            default_type                => 'HTMLTemplate',
            auto_add_template_extension => 0,
        );

    The *plugin configuration* parameters and their defaults are as follows:

    default_type
    type
        The default type of template for this named configuration. Should be
        the name of a driver in the
        "CGI::Application::Plugin::AnyTemplate::Driver" namespace:

            Type                Driver
            ----                ------
            HTMLTemplate        CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplate
            HTMLTemplateExpr    CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplateExpr
            TemplateToolkit     CGI::Application::Plugin::AnyTemplate::Driver::TemplateToolkit
            Petal               CGI::Application::Plugin::AnyTemplate::Driver::Petal

    include_paths
        Include Paths (sometimes called search paths) are used by the
        various template backends to find filenames that aren't fully
        qualified by an absolute path. Each directory is searched in turn
        until the template file is found.

        Can be a single string or a reference to a list.

    auto_add_template_extension
        Add a template-system specific extension to template filenames.

        So, if this feature is enabled and you provide the filename
        "myfile", then the actual filename will depend on the current
        template driver:

            Driver                 Template
            ------                 --------
            HTMLTemplate           myfile.html
            HTMLTemplateExpr       myfile.html
            TemplateToolkit        myfile.tmpl
            Petal                  myfile.xhtml

        The per-type extension is controlled by the driver config for each
        "AnyTemplate" driver (see below under "Driver and Native
        Configuration" for how to set this).

        The "auto_add_template_extension" feature is on by default. To
        disable it, pass a value of zero:

            $self->template->config(
                auto_add_template_extension => 0,
            );

        The automatic extension feature is not just there to save typing -
        it's actually there so you can have templates of different types
        sitting in the same directory.

            sub my_runmode {
                my $self = shift;
                $self->template->fill;
            }

        Then in your template path you can have three files:

            my_runmode.html
            my_runmode.tmpl
            my_runmode.xhtml

        Then you can change which templates is used by changing the value of
        "type" that you pass to "$self->template->config".

        For applications that want to dynamically choose their template
        system without changing app code, it's a cleaner solution to use the
        extensions than trying to swap template paths at runtime. Even if
        you keep each type of template in its own directory, it's simpler to
        include all the directories all the time and use different
        extensions for different template types.

    template_filename_generator
        If you don't pass a filename to "load", one will be generated for
        you based on the current run mode. If you want to customize this
        process, you can pass a reference to a subroutine to do the
        translation. This subroutine will be passed a reference to the
        CGI::Application $self object.

        Here is a subroutine that emulates the built-in behaviour of
        "AnyTemplate":

            $self->template->config(
                template_filename_generator => sub {
                    my ($self, $calling_method_name) = @_;
                        return $self->get_current_runmode;
                    }
                }
            );

        Here is an example of using a template filename generator to make
        full templates with full paths based on the module name as well as
        the current run mode (this is similar to how
        CGI::Application::Plugin::TT generates its template filenames):

            package My::WebApp;
            use File::Spec;

            sub cgiapp_init {
                my $self = shift;

                $self->template->config(
                    template_filename_generator => sub {
                        my $self     = shift;
                        my $run_mode = $self->get_current_runmode;
                        my $module   = ref $self;

                        my @segments = split /::/, $module;

                        return File::Spec->catfile(@segments, $run_mode);
                    }
                );
            }

            sub run_mode {
                my $self = shift;
                $self->template->load;  # loads My/WebApp/run_mode.html
            }

            sub other_run_mode {
                my $self = shift;
                $self->template->load;  # loads My/WebApp/other_run_mode.html
            }

        Note that if the "auto_add_template_extension" option is on (which
        it is by default), then the extension will be added to your
        generated filename after you return it. If you do not want this to
        happen, then set "auto_add_template_extension" to a false value.

    component_handler_class
        Normally, component embedding is handled by
        CGI::Application::Plugin::AnyTemplate::ComponentHandler. If you want
        to use a different class for this purpose, specify the class name as
        the value of this paramter.

        It still has to provide the same interface as
        CGI::Application::Plugin::AnyTemplate::ComponentHandler. See the
        source code of that module for details.

    return_references
        When true (the default), "output" will return a reference to a
        string rather than a copy. Normally this won't matter. For instance,
        "CGI::Application" doesn't care whether you return a string or a
        reference to a string from your run modes.

        However, if you want to manipulate the output of the $html returned
        from the template, you may find it convenient to make "output"
        return a string instead of a reference. Especially if you are
        converting old code based on HTML::Template which expects "output"
        to return a string.

   Driver and Native Configuration
    You can configure all the drivers at once with a single call to
    "config", by including subsections for each driver type:

        $self->template->config(
            default_type => 'HTMLTemplate',
            HTMLTemplate => {
                cache              => 1,
                global_vars        => 1,
                die_on_bad_params  => 0,
                template_extension => '.html',
            },
            HTMLTemplateExpr => {
                cache              => 1,
                global_vars        => 1,
                die_on_bad_params  => 0,
                template_extension => '.html',
            },
            HTMLTemplatePluggable => {
                cache              => 1,
                global_vars        => 1,
                die_on_bad_params  => 0,
                template_extension => '.html',
            },
            TemplateToolkit => {
                POST_CHOMP         => 1,
                template_extension => '.tmpl',
            },
            Petal => {
                error_on_undef     => 0,
                template_extension => '.xhtml',
            },
        );

    Each driver knows how to separate its own configuration from the
    configuration belonging to the underlying template system.

    For instance in the example above, the "HTMLTemplate" driver knows that
    "template_extension" is a driver config parameter, but
    "cache_global_vars" and "die_on_bad_params" are all HTML::Template
    configuration parameters.

    Similarly, The "TemplateToolkit" driver knows that template_extension is
    a driver config parameter, but "POST_CHOMP" is a "Template::Toolkit"
    configuration parameter.

    For details on driver configuration, see the docs for the individual
    drivers:

    CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplate
    CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplateExpr
    CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplatePluggable
    CGI::Application::Plugin::AnyTemplate::Driver::TemplateToolkit
    CGI::Application::Plugin::AnyTemplate::Driver::Petal

   Copying Query data into Templates
    This feature is now deprecated and will be removed in a future release.

    When you enable this feature all data in "$self->query" are copied into
    the template object before the template is processed.

    For the "HTMLTemplate", "HTMLTemplateExpr" and "HTMLTemplatePluggable"
    drivers this is done with the "associate" feature of HTML::Template and
    HTML::Template::Expr, respectively:

        my $template = HTML::Template->new(
            associate => $self->query,
        );

    For the other systems, this feature is emulated, by copying the query
    params into the template params before the template is processed.

    To enable this feature, pass a true value to "associate_query" or
    "emulate_associate_query" (depending on the template system):
    $self->template->config( default_type => 'HTMLTemplate', HTMLTemplate =>
    { associate_query => 1, }, HTMLTemplateExpr => { associate_query => 1,
    }, HTMLTemplatePluggable => { associate_query => 1, }, TemplateToolkit
    => { emulate_associate_query => 1, }, Petal => { emulate_associate_query
    => 1, }, );

    The reason this feature is now disabled by default is that it poses a
    potential XSS (Cross Site Scripting) security risk.

    The reason this feature is now deprecated is that in an ideal world
    developers shouldn't have to flatten objects and hashes in order to make
    them available to their templates. They should be able to pass the query
    object (or another object such as a config object) directly into the
    template:

        $template->param(
            'query' => $self->query,
            'cfg'   => $self->cfg,
            'ENV'   => $ENV,
        );

    And in the template retrieve parameters directly:

        your username: [% query.param('username') %]
        administrator: [% cfg.admin %]
        hostname:      [% ENV.SERVER_NAME %]

    This approach works with Template::Toolkit, Petal, and
    HTML::Template::Pluggable (via the HTML::Template::Plugin::Dot plugin).

    Note that "associate" and "associate_query" are not compatible. So if
    you want to associate the query and an additional object, pass a list to
    "associate":

        $template->config(
            HTMLTemplate => {
                associate => [$self->query, $self->conf]
            }
        );

  load
    Create a new template object and configure it.

    This can be as simple (and magical) as:

        my $template = $self->template->load;

    When you call "load" with no parameters, it uses the default template
    type, the default template configuration, and it determines the name of
    the template based on the name of the current run mode. It determines
    the current run mode by calling "$self->get_current_runmode".

    If you want to have the current runmode updated when you pass control to
    another runmode, use the CGI::Application::Plugin::Forward module:

        use CGI::Application::Plugin::Forward;

        sub first_runmode {
            my $self = shift;
            return $self->forward('second_runmode');
        }
        sub second_runmode {
            my $self = shift;
            my $template = $self->template->load;  # loads 'second_runmode.html'
        }

    If instead you call "$self->other_method" directly, the value of
    "$self->get_current_runmode" will not be updated:

        sub first_runmode {
            my $self = shift;
            return $self->other_method;
        }
        sub other_method {
            my $self = shift;
            my $template = $self->template->load;  # loads 'first_runmode.html'
        }

    If you want to override the way the default template filename is
    generated, you can do so with the "template_filename_generator"
    configuration parameter.

    If you call "load" with one paramter, it is taken to be either the
    filename or a reference to a string containing the template text:

        my $template = $self->template->load('somefile');
        my $template = $self->template->load(\$some_text);

    If the parameter "auto_add_template_exension" is true, then the
    appropriate extension will be added for this template type.

    If you call "load" with more than one parameter, then you can specify
    filename and configuration paramters directly:

        my $template = $self->template->load(
            file                        => 'some_file.tmpl',
            type                        => 'HTMLTemplate',
            auto_add_template_extension => 0,
            add_include_paths           => '..',
            HTMLTemplate => {
                die_on_bad_params => 1,
            },
        );

    To initialize the template from a string rather than a file, use:

        my $template = $self->template->load(
            string =>  \$some_text,
        );

    The configuration parameters you pass to "load" are merged with the
    configuration that was passed to "config".

    You can include any of the configuration parameters that you can pass to
    config, plus the following extra parameters:

    file
        If you are loading the template from a file, then the "file"
        parameter contains the template's filename.

    string
        If you are loading the template from a string, then the "string"
        parameter contains the text of the template. It can be either a
        scalar or a reference to a scalar. Both of the following will work:

            # passing a string
            my $template = $self->template->load(
                string => $some_text,
            );

            # passing a reference to a string
            my $template = $self->template->load(
                string => \$some_text,
            );

    add_include_paths
        Additional include paths. These will be merged with "include_paths"
        before being passed to the template driver.

    The "load" method returns a template driver object. See below under
    "DRIVER METHODS", for how to use this object.

  fill
    Fill is a convenience method which in a single step creates the
    template, fills it with the template paramters and returns its output.

    You can call it with or without a filename (or string ref).

    The code:

        $self->template->fill('filename', \%params);

    is equivalent to:

        my $template = $self->template->load('filename');
        $template->output(\%params);

    And the code:

        $self->template->fill(\$some_text, \%params);

    is equivalent to:

        my $template = $self->template->load(\$some_text);
        $template->output(\%params);

    And the code:

        $self->template->fill(\%params);

    is equivalent to:

        my $template = $self->template->load;
        $template->output(\%params);

    And the code:

        $self->template->fill('filename');

    is equivalent to:

        my $template = $self->template->load('filename');
        $template->output;

    And the code:

        $self->template->fill(\$some_text);

    is equivalent to:

        my $template = $self->template->load(\$some_text);
        $template->output;

    And the code:

        $self->template->fill;

    is equivalent to:

        my $template = $self->template->load;
        $template->output;

  process
    "process" is an alias for "fill".

APPLICATION METHODS
    These methods are called directly on your application's $self object.

  load_tmpl
    This is an emulation of CGI::Application's built-in "load_tmpl" method.
    For instance:

        $self->load_tmpl('some_template.html');

    It is not exported by default. To enable it, use:

        use CGI::Application::Plugin::AnyTemplate qw/:load_tmpl/;

    You can call it the same way as documented in "CGI::Application" and it
    will have the same effect. However, it will respect the current template
    "type", so you can still use it to fill templates of different backends.

    The idea is that you can take an existing CGI::Application-based webapp
    which uses "HTML::Template" templates, and add the following code to it:

        use CGI::Application::Plugin::AnyTemplate qw/:load_tmpl/;

        sub setup {
            my $self = shift;
            $self->template->config(type => TemplateToolkit);
        }

    This will change all existing calls to load_tmpl within your application
    to use Template::Toolkit based templates.

    Calling:

        my $template = $self->load_tmpl('some_template.html');

    It is the equivalent of calling:

        my $template = $self->template->load(
            file => 'some_template.html',
            auto_add_template_extension => 0,
        );

    If you add extra options to "load_tmpl", these will be assumed to be
    HTML::Template specific options, with the exception of the "path"
    option, which will be extracted and used as 'add_include_paths':

        my $template = $self->load_tmpl('some_template.html',
            cache => 0,
            path  => '/path/to/templates',
        );

    This will get translated into:

        my $template = $self->template->load(
            file => 'some_template.html',
            auto_add_template_extension => 0,
            add_include_paths => '/path/to/templates',
            HTMLTemplate => {
                cache => 0,
            }
        );

    Note that if you specify any HTML::Template-specific options here, they
    will completely overwrite any options that you passed to config.

    Some notes and caveats about using the "load_tmpl" method:

    *   This method only works for the default template configuration (i.e.
        "$self->template()"). If you set up a named configuration (e.g.
        "$self->template('myconfig')") there is no way to access it with
        "load_tmpl". Since plugins should be using named configurations,
        this means that the "load_tmpl" method should not be used by
        plugins. See "NOTES FOR AUTHORS OF PLUGINS AND REUSABLE
        APPLICATIONS", below.

    *   The "load_tmpl" method does not automatically add an extension to
        the filename you pass to it, even if you have
        "auto_add_template_extension" set to a true value in your call to
        "$self->template->config".

    *   The "load_tmpl" method ignores always returns a string, not a
        reference to a string. It ignores the setting of the
        "returns_references" option.

  tmpl_path
    You can set the template "include_paths" by calling
    "$self->tmpl_path('/path/to/templates')".

    You can also do so by passing a value to the "TMPL_PATH" parameter to
    your application's "new" method:

        my $webapp = App->new(
            TMPL_PATH => '/path/to/templates',
        );

    Paths that you set via "tmpl_path"/"TMPL_PATH" will be put last in the
    list of include paths, after "add_include_paths" and "include_paths".

DRIVER METHODS
    These are the most commonly used methods of the "AnyTemplate" driver
    object. The driver is what you get back from calling
    "$self->template->load".

  param
    The "param" method gets and sets values within the template.

        my $template = $self->template->load;

        my @param_names = $template->param();

        my $value = $template->param('name');

        $template->param('name' => 'value');
        $template->param(
            'name1' => 'value1',
            'name2' => 'value2'
        );

    It is designed to behave similarly to the "param" method in other
    modules like CGI and HTML::Template.

  get_param_hash
    Returns the template variables as a hash of names and values.

        my %params     = $self->template->get_param_hash;

    In a scalar context, returns a reference to the hash used internally to
    contain the values:

        my $params_ref = $self->template->get_param_hash;

        $params_ref->{'foo'} = 'bar';  # directly change parameter 'foo'

  output
    Returns the template with all the values filled in.

        return $template->output;

    You can also supply names and values to the template at this stage:

        return $template->output('name' => 'value', 'name2' => 'value2');

    If "return_references" option is set to true, then the return value of
    "output" will be a reference to a string. If the "return_references"
    option is false, then a copy of the string will be returned. By default
    "return_references" is true.

    When you call the "output" method, any components embedded in the
    template are run. See "EMBEDDED COMPONENTS", below.

PRE- AND POST- PROCESS
    There are several ways to customize the template process. You can modify
    the template parameters before the template is filled, and you can
    modify the output of the template after it has been filled.

    Multiple applications and plugins can hook into the template process
    pipeline, each making changes to the template input and output.

    For instance, it will be possible to make a general-purpose
    "CGI::Application" plugin that adds arbitrary data to each new template
    (such as query parameters or configuration data).

    Note that the API has changed for version 0.10 in a
    non-backwards-compatible way in order to use the new hook system
    provided by recent versions of "CGI::Application".

  The load_tmpl hook
    The "load_tmpl" hook is designed to be compatible with the "load_tmpl"
    hook defined by "CGI::Application" itself.

    The "load_tmpl" hook is called before the template object is created.
    Any callbacks that you register to this hook will be called before each
    template is loaded. Register a "load_tmpl" callback with:

       $self->add_callback('load_tmpl',\&my_load_tmpl);

    When the "load_tmpl" callback is executed it will be passed three
    arguments (*adapted from the* CGI::Application *docs*):

     1. A hash reference of the extra params passed into C<load_tmpl>
        (ignored by AnyTemplate with the exception of 'path')

     2. Followed by a hash reference to template parameters.
        You can modify this hash by reference to affect values that are
        actually passed to the param() method of the template object.

     3. The name of the template file.

    Here's an example stub for a load_tmpl() callback:

        sub my_load_tmpl_callback {
            my ($self, $ht_params, $tmpl_params, $tmpl_file) = @_;
            # modify $tmpl_params by reference...
        }

    Currently, of all the params in $ht_params, all but 'path' are ignored,
    because these are specific to "HTML::Template". If you want to write a
    generic callback that needs to be able to access or modify
    "HTML::Template" parameters then let me know, or add a feature request
    on <http://rt.cpan.org>.

    The "path" param of $ht_params is initially set to the value of
    "add_include_paths" (if set). Your callback can modify the "path" param,
    and "add_include_param" will be set to the result.

    Plugin authors who want to provide template processing features are
    encouraged to use the 'load_tmpl' hook when possible, since it will work
    both with AnyTemplate and with CGI::Application's built-in "load_tmpl".

  The template_pre_process and template_post_process hooks
    Before the template output is generated, the "template_pre_process" hook
    is called. Any callbacks that you register to this hook will be called
    before each template is processed. Register a "template_pre_process"
    callback as follows:

        $self->add_callback('template_pre_process', \&my_tmpl_pre_process);

    Pre-process callbacks will be passed a reference to the $template
    object, and can can modify the parameters passed into the template by
    using the "param" method:

        sub my_tmpl_pre_process {
            my ($self, $template) = @_;

            # Change the internal template parameters by reference
            my $params = $template->get_param_hash;

            foreach my $key (keys %$params) {
                $params{$key} = to_piglatin($params{$key});
            }

            # Can also set values using the param method
            $template->param('foo', 'bar');

        }

    After the template output is generated, the "template_post_process" hook
    is called. You can register a "template_post_process" callback as
    follows:

        $self->add_callback('template_post_process', \&my_tmpl_post_process);

    Any callbacks that you register to this hook will be called after each
    template is processed, and will be passed both a reference to the
    template object and a reference to the output generated by the template.
    This allows you to modify the output of the template:

        sub my_tmpl_post_process {
            my ($self, $template, $output_ref) = @_;

            $$output_ref =~ s/foo/bar/;
        }

EMBEDDED COMPONENTS
  Introduction
    "CGI::Application::Plugin::AnyTemplate" allows you to include
    application components within your templates.

    For instance, you might include a *header* component a the top of every
    page and a *footer* component at the bottom of every page.

    These componenets are actually first-class run modes. When the template
    engine finds a special tag marking an embedded component, it passes
    control to the run mode of that name. That run mode can then do whatever
    a normal run mode could do. But typically it will load its own template
    and return the template's output.

    This output returned from the embedded run mode is inserted into the
    containing template.

    The syntax for embed components is specific to each type of template
    driver.

  Syntax
    HTML::Template syntax:

        <TMPL_VAR NAME="CGIAPP_embed('some_run_mode')">

    HTML::Template::Expr syntax:

        <TMPL_VAR EXPR="CGIAPP_embed('some_run_mode')">

    HTML::Template::Pluggable syntax:

        <TMPL_VAR EXPR="cgiapp.embed('some_run_mode')">

    Template::Toolkit syntax:

        [% CGIAPP.embed("some_run_mode") %]

    Petal syntax:

        <span tal:replace="structure CGIAPP/embed 'some_run_mode'">
            this text gets replaced by the output of some_run_mode
        </span>

  Getting Template Variables from the Containing Template
    The component run mode is passed a reference to the template object that
    contained the component. The component run mode can use this object to
    access the params that were passed to the containing template.

    For instance:

        sub header {
            my ($self, $containing_template, @other_params) = @_;

            my %tmplvars = (
                'title' => 'My glorious home page',
            );

            my $template = $self->template->load;

            $template->param(%tmplvars, $containing_template->get_param_hash);
            return $template->output;
        }

    In this example, the template values of the enclosing template would
    override any values set by the embedded component.

  Passing Parameters
    The template can pass parameters to the target run mode. These are
    passed in after the reference to the containing template object.

    Parameters can either be literal strings, specified within the template
    text, or they can be keys that will be looked up in the template's
    params.

    Literal strings are enclosed in double or single quotes. Param keys are
    barewords.

    HTML::Template syntax:

        <TMPL_VAR NAME="CGIAPP_embed('some_run_mode', param1, 'literal string2')">

    *Note that HTML::Template doesn't support this type of callback
    natively* *and that this behaviour is emulated by the HTMLTemplate
    driver* *see the docs to*
    CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplate *for
    limitations to the emulation*.

    HTML::Template::Expr syntax:

        <TMPL_VAR EXPR="CGIAPP_embed('some_run_mode', param1, 'literal string2')">

    HTML::Template::Pluggable syntax:

        <TMPL_VAR EXPR="cgiapp.embed('some_run_mode', param1, 'literal string2')">

    Template::Toolkit syntax:

        [% CGIAPP.embed("some_run_mode", param1, 'literal string2' ) %]

    Petal syntax:

        <span tal:replace="structure CGIAPP/embed 'some_run_mode' param1 'literal string2' ">
            this text gets replaced by the output of some_run_mode
        </span>

NOTES FOR AUTHORS OF PLUGINS AND REUSABLE APPLICATIONS
    If you are writing a CGI::Application plugin module, or you are writing
    a "CGI::Application" program that will be distributed to other people
    (e.g. on CPAN), then it's important to take steps to prevent your
    application's use of CGI::Application::Plugin::AnyTemplate from
    conflicting with other plugins or with your end users.

    When a plugin that uses CGI::Application::Plugin::AnyTemplate calls:

       $self->template->config(...)

    It overwrites any existing template configuration with the new settings.
    So if two plugins do that, they probably clobber each other.

    However, CGI::Application::Plugin::AnyTemplate has the feature of named
    independent configs:

       $self->template('your_module')->config(...)
       $self->template('my_plugin')->config(...)

    These configs remain separate from each other. However, you have to keep
    using these names throughout your module, even when you load and fill
    the template. For instance:

       sub my_runmode {
           my $self = shift;
           my $template = $self->template('my_plugin')->load;
           $template->output;
       }

       sub your_runmode {
           my $self = shift;
           my %params;
           $self->template('your_module')->fill(\%params);
       }

    It's uglier and more verbose, but it also prevents plugins from stepping
    on each other's toes.

    CGI::Application plugins that use CGI::Application::Plugin::AnyTemplate
    should default to using their own package name for the AnyTemplate
    config name:

       $self->template(__PACKAGE__)->config(...);
       $self->template(__PACKAGE__)->fill(...);

CHANGING THE NAME OF THE 'template' METHOD
    If you want to access the features of this module using a method other
    than "template", you can do so via Anno Siegel's Exporter::Renaming
    module (available on CPAN).

    For instance, to use syntax similar to CGI::Application::Plugin::TT:

        use Exporter::Renaming;
        use CGI::Application::Plugin::AnyTemplate Renaming => [ template => tt];

        sub cgiapp_init {
            my $self = shift;

            my %params = ( ... );

            # Set config file and other options
            $self->tt->config(
                default_type => 'TemplateToolkit',
            );

        }

        sub my_runmode {
            my $self = shift;
            $self->tt->process('file', \%params);
        }

    And to use syntax similar to CGI::Application's "load_tmpl" mechanism:

        use Exporter::Renaming;
        use CGI::Application::Plugin::AnyTemplate Renaming => [ template => tmpl];

        sub cgiapp_init {
            my $self = shift;

            # Set config file and other options
            $self->tmpl->config(
                default_type => 'HTMLTemplate',
            );

        }

        sub my_runmode {
            my $self = shift;

            my %params = ( ... );

            my $template = $self->tmpl->load('file');
            $template->param(\%params);
            $template->output;
        }

AUTHOR
    Michael Graham, "<mgraham@cpan.org>"

ACKNOWLEDGEMENTS
    I originally wrote this to be a subsystem in Richard Dice's
    CGI::Application-based framework, before I moved it into its own module.

    Various ideas taken from CGI::Application (Jesse Erlbaum),
    CGI::Application::Plugin::TT (Cees Hek) and "Text::Boilerplate" (Stephen
    Nelson).

    "Template::Toolkit" singleton support code stolen from
    CGI::Application::Plugin::TT.

BUGS
    Please report any bugs or feature requests to
    "bug-cgi-application-plugin-anytemplate@rt.cpan.org", or through the web
    interface at <http://rt.cpan.org>. I will be notified, and then you'll
    automatically be notified of progress on your bug as I make changes.

SOURCE
    The source code repository for this module can be found at
    http://github.com/mgraham/CAP-AnyTemplate/

SEE ALSO
        CGI::Application::Plugin::AnyTemplate::Base
        CGI::Application::Plugin::AnyTemplate::ComponentHandler
        CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplate
        CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplateExpr
        CGI::Application::Plugin::AnyTemplate::Driver::HTMLTemplatePluggable
        CGI::Application::Plugin::AnyTemplate::Driver::TemplateToolkit
        CGI::Application::Plugin::AnyTemplate::Driver::Petal

        CGI::Application

        Template::Toolkit
        HTML::Template

        HTML::Template::Pluggable
        HTML::Template::Plugin::Dot

        Petal

        Exporter::Renaming

        CGI::Application::Plugin::TT

COPYRIGHT & LICENSE
    Copyright 2005 Michael Graham, All Rights Reserved.

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