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Package TWiki::Plugins

This module defines the singleton object that handles Plugins loading, initialization and execution.

This class uses Chain of Responsibility (GOF) pattern to dispatch handler calls to registered plugins.

Note that as of version 1.026 of this module, TWiki internal methods are no longer available to plugins. Any calls to TWiki internal methods must be replaced by calls via the $SESSION object in this package, or via the Func package. For example, the call:

my $pref = TWiki::getPreferencesValue('URGH');

should be replaced with

my $pref = TWiki::Func::getPreferencesValue('URGH');

and the call

my $t = TWiki::writeWarning($message);

should be replaced with

my $pref = $TWiki::Plugins::SESSION->writeWarning($message);

Methods in other modules such as Store must be accessed through the relevant TWiki sub-object, for example


should be replaced with


Note that calling TWiki internal methods is very very bad practice, and should be avoided wherever practical.

The developers of TWiki reserve the right to change internal methods without warning, unless those methods are clearly marked as PUBLIC. PUBLIC methods are part of the core specification of a module and can be trusted.


This is the version number of the plugins package. Use it for checking if you have a recent enough version.


This is a reference to the TWiki session object. It can be used in plugins to get at the methods of the TWiki kernel.

You are highly recommended to only use the methods in the Func interface, unless you have no other choice, as kernel methods may change between TWiki releases.

ClassMethod new ($session)

Construct new singleton plugins collection object. The object is a container for a list of plugins and the handlers registered by the plugins. The plugins and the handlers are carefully ordered.

ObjectMethod finish ()

Break circular references.

ObjectMethod load ($allDisabled) -> $loginName

Find all active plugins, and invoke the early initialisation. Has to be done after prefs are read.

Returns the user returned by the last initializeUserHandler to be called.

If allDisabled is set, no plugin handlers will be called.

ObjectMethod settings ()

Push plugin settings onto preference stack

ObjectMethod enable ()

Initialisation that is done after the user is known.

ObjectMethod getPluginVersion () -> $number

Returns the $TWiki::Plugins::VERSION number if no parameter is specified, else returns the version number of a named Plugin. If the Plugin cannot be found or is not active, 0 is returned.

ObjectMethod addListener ($command,$handler)

  • $command - name of the event
  • $handler - the handler object.

Add a listener to the end of the list of registered listeners for this event. The listener must implement invoke($command,...), which will be triggered when the event is to be processed.

ObjectMethod dispatch ($handlerName,...)

Dispatch the given handler, passing on ... in the parameter vector

ObjectMethod haveHandlerFor ($handlerName) -> $boolean

  • $handlerName - name of the handler e.g. preRenderingHandler
Return: true if at least one plugin has registered a handler of this type.

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Topic revision: r4 - 2010-05-29 - TWikiContributor
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