smarty/docs/programmers/plugins/plugins-writing.md

Writing Plugins

Plugins can be either loaded by Smarty automatically from the filesystem or they can be registered at runtime via one of the register_* API functions. They can also be unregistered by using unregister_* API functions.

For the plugins that are registered at runtime, the name of the plugin function(s) does not have to follow the naming convention.

As a general rule, the currently evaluated template's Smarty_Internal_Template object is always passed to the plugins as the last parameter with two exceptions:

• modifiers do not get passed the Smarty_Internal_Template object at all

• blocks get passed $repeat after the Smarty_Internal_Template object to keep backwards compatibility to older versions of Smarty.