/ 
CGI-Application-Plugin-AutoRunmode-0.06
River stage one • 6 direct dependents • 6 total dependents
/ CGI::Application::Plugin::AutoRunmode

NAME

CGI::Application::Plugin::AutoRunmode - CGI::App plugin to automatically register runmodes

SYNOPSIS

Using subroutine attributes:

package MyApp;
use base 'CGI::Application';
use CGI::Application::Plugin::AutoRunmode;

sub my_run_mode : Runmode {
	# do something here
}

sub another_run_mode : Runmode {
	# do something else
}

# you now have two run modes
# "my_run_mode" and "another_run_mode"

Using a delegate object

  	package MyAppRunmodes;
	# the delegate class
		sub my_run_mode  {
			my ($app, $delegate) = @_;
				# do something here
		}
	    
		sub another_run_mode  {
				# do something else
		}
		
	package MyApp;
   	use base 'CGI::Application';
	   
		sub setup{
			my ($self) = @_;
			my $delegate = 'MyAppRunmodes';
				# $delegate can be a class name or an object
			$self->param('::Plugin::AutoRunmode::delegate' => $delegate);
		}
	
	 # you now have two run modes
	 # "my_run_mode" and "another_run_mode"

DESCRIPTION

This plugin for CGI::Application provides easy ways to setup run modes. You can just write the method that implement a run mode, you do not have to explicitly register it with CGI::App anymore.

There are two approaches: You can flag methods in your CGI::App subclass with the attribute "Runmode", or you can assign a delegate object, all whose methods will become runmodes (you can also mix both approaches).

Delegate runmodes receive two parameters: The first one is the CGI::App instance, followed by the delegate instance or class name. This can be useful if you have delegate objects that contain state.

It both cases, the resulting runmodes will have the same name as the subroutine that implements them. They are activated by a cgiapp_prerun hook provided by this plugin (if you are using CGI::Application older than version 4, hooks are not available, and you can import a cgiapp_prerun method instead).

EXPORT

This module needs to export some symbols to do its job.

First of all, there are the handlers for the Runmode attribute.

In addition to that, the cgiapp_prerun hook is installed in your application class. This is not done as an export per se, but the hook installation is still done in the import subroutine. Sound confusing, is confusing, but you do not really need to know what is going on exactly, just keep in mind that in order to let things go on, you have to "use" the module with the default exports:

use CGI::Application::Plugin::AutoRunmode;

and not

use CGI::Application::Plugin::AutoRunmode ();
	# this will disable the Runmode attributes
	# DO NOT DO THIS

You can also explicitly import the cgiapp_prerun method. This will disable the installation of the hook. Basically, you only want to do this if you are using CGI::Application prior to version 4, where hooks are not supported.

use CGI::Application::Plugin::AutoRunmode 
	qw [ cgiapp_prerun];
	# do this if you use CGI::Application version 3.x

How does it work?

After CGI::App has determined the name of the run mode to be executed in the normal way, cgiapp_prerun checks if such a run mode exists in the map configured by $self->run_modes().

If the run mode already exists, it gets executed normally (this module does nothing). This means that you can mix the ways to declare run modes offered by this plugin with the style provided by core CGI::App.

If that is not the case, it tries to find a method of the same name in the application class (or its superclasses) that has been flagged as a Runmode. If it finds one, it augments the mapping with a subroutine reference to that method.

If that step fails, it looks if a delegate has been defined and searches the methods of that delegate object for one that matches the name of the runmode.

The runmode can then be executed by CGI::App as if it had been set up by $self->run_modes() in the first place.

Does it still work if I change the run-mode in cgiapp_prerun ?

If you have a cgiapp_prerun method and change the run-mode there, the installed hook will not be able to catch it (because of the ordering of hooks).

So, if you do that, you have to explicitly make this call before returning from cgiapp_prerun:

CGI::Application::Plugin::AutoRunmode::cgiapp_prerun($self);

Again, this is only necessary if you change the run-mode (to one that needs the auto-detection feature).

Also, this kind of code can be used with CGI::App 3.x if you have a cgiapp_prerun.

A word on security

The whole idea of this module (to reduce code complexity by automatically mapping a URL to a subroutine that gets executed) is a potential security hazard and great care has to be taken so that a remote user cannot run code that you did not intend them to.

In order to prevent a carefully crafted URL to access code in other packages, this module disallows non-word characters (such as : ) in run mode names.

Also, you have to make sure that when using a delegate object, that it (and its superclasses) only contain run modes (and no other subroutines).

The following run mode names are disallowed by this module:

can isa VERSION AUTOLOAD new DESTROY

SEE ALSO

AUTHOR

Thilo Planz, <thilo@cpan.org>

COPYRIGHT AND LICENSE

Copyright 2004/05 by Thilo Planz

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