Hello everyone

In joomla 3, the developer is a very important element inflection plugin
There are many types of plugin in joomla3 and even can also add their own
like the system plug
i will explains how to call plugin

//captcha plugin
JPluginHelper::importPlugin('captcha');//load plugin
$dispatcher = JDispatcher::getInstance(); //call dispatcher
//there can call plugin to get verify code html
//array(NULL) is params
$verifycode = $dispatcher->trigger('onDisplay',array('name','id','class'));//run plugin function
how about the plugin code?
in plugins/captcha/recaptcha/recaptcha.php
there is
public function onDisplay($name, $id = 'dynamic_recaptcha_1', $class = '')
this function
so we can set the params in function
to plugin

For me, the main plug positioning for [expansion]
Although component itself is already have helpers
But the helper more similar to commonly used functions in the component
the plugin can call in any component
And with joomla3 system architecture
It allows developers to function more customization, more flexible
For example: the editor extension can also use plugin expansion