Plug-in
From Joomla! Documentation
A plugin is a kind of Joomla! extension. Plugins provide functions which are associated with trigger events. Joomla provides a set of core plugin events, but any extension can fire (custom) events. When a particular event occurs, all plugin functions of the type associated with the event are executed in sequence. This is a powerful way of extending the functionality of Joomla. It also offers extension developers a way to allow other extensions to respond to their actions, making extensions extensible.
The Joomla! plugin architecture follows the Observer design pattern. The JPlugin class provides the means to register custom plugin code with core or custom events. The JEventDispatcher class is an event handler which calls all plugins registered for a particular event, when that event is triggered. In Joomla 4.x this has been moved to the \Joomla\Event\Dispatcher class in Joomla, and additionally follows the Mediator design pattern
Consulte também: Componente, Módulo, Modelo
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Principiante
Para saber como instalar e utilizar um plug-in no Joomla é recomendado ler S:MyLanguage/Administration of a Plugin in Joomla
Intermediário
Para compreender melhor os plug-ins, deverá criar um plug-in básico para o Joomla!.
Se tiver um plug-in de conteúdo básico num módulo ou componente personalizado, nós recomendamos a leitura de Triggering content plugins in your extension.
Avançado
Para perceber os princípios sobre os quais o sistema de Plug-in funciona Plugin Developer Overview. Para depois implementar isto num componente tem de o criar recomenda-se que leia Supporting plugins in your component.
Utilizar Plug-ins
Plugins are grouped together depending on which event they run on. For developer reference there is a full list of plugins grouped by their event type. Please note, the names of a lot of events changed between the Joomla 1.5 and Joomla 2.5 versions. Here is a full list of the 1.5 to 2.5 plugin event name changes. There are also several simple tutorials on making some sample plugins running on some of these events to help running searches on extensions using both the search and smart search components:
Existem outros tutoriais que utilizam triggers de utilizador sobre como criar um plug-in de autenticação para ajudar os mesmos a iniciarem a sessão no Joomla e criar um plug-in de perfil para o Joomla.
Um exemplo mais complexo da utilização de plug-ins para criar um novo router do sistema para criar URLs também está disponível (apenas 
).