pluggy and the Plugin Architecture#
pluggy ([1], [2], [3]) is at the heart of pytask and enables its plugin system. The mechanism to achieve extensibility is called hooking.
At specific points, pytask, or more generally the host, implements entry-points called hook specifications. At these entry-points, the host sends a message to all plugins which target this entry-point. The message’s recipient is implemented by the plugin and called a hook implementation. The hook implementation receives the message and can decide whether to send a response or not. Then, the host gets the responses and can choose whether to process all or just the first valid return.
In contrast to some other mechanisms to change the behavior of a program (like method overriding and monkey patching), hooking excels at allowing multiple plugins to work alongside each other.
It is the host’s responsibility to design the entry-points in a way such that
plugins can target very specific entry-points of the application and achieve their goal efficiently.
many plugins can work alongside each other.
the necessary knowledge about pytask to implement a plugin is somewhat proportional to the complexity of the plugin’s provided functionality.