MyPlaza modules are very similar to MyBB plugins. This was to make the transition from developing MyBB plugins, to MyPlaza modules as smooth as possible. In fact, MyBB plugins should run fine as a MyPlaza module, with one exception...
MyPlaza modules, by design, may be include'd at various locations. Also, many simple modules will not need to be include'd on every page, unlike MyBB plugins are - this is done to save some time parsing the extra code.
Because of this, I have made a special _plugin() function, in which you should place everything that is to be executed, like a MyBB plugin (ie plugin hooks). Obviously, code outside any functions will be executed when the file is include'd, however, MyPlaza will not include modules which do not have a _plugin() function, as a MyBB plugin.
In other words, if you add a blank _plugin() function, ie function myplugin_plugin(){} to an existing MyBB plugin, it should run fine as a MyPlaza module (with some minor exceptions).
_info() function.
_info() function for MyBB plugins. Basically, it's a required function, which returns information about the plugin. MyPlaza extends MyBB's _info() with a few extra optional fields: compatibility is simply an array of versions of MyPlaza which the module is compatible with - this is just used to present the compatibility warning in the AdminCP; update_check_url is the URL which MyPlaza accesses if checking if a newer version of the module is available; update_download_url is the URL from which MyPlaza downloads updates for the module (more information about automatic updating may be provided in a later version of this documentation).
_activate() function in MyBB plugins. This function is called when a user activates the module/plugin in the AdminCP.
_deactivate() function in MyBB plugins. This function is called when a user deactivates the module/plugin in the AdminCP.
myplaza_langload() is called (which is done automatically at various places to make things more convenient).
$item variable. You'll need to return a boolean value with this function, indicating success (true) or failure (false).
$process variable is true when settings should be processed, or false otherwise.