A metaphor for Drupal module's inner workings

Question

What is the best application workflow metaphor for Drupal module? In PHP frameworks we think MVC-style. How do we think inside Drupal?

Asumming I am writing some user-or

Answer 1

Modules in drupal are best thought of as a collection of functions (implementation of drupal's "hooks") which are called when certain "events" happen in the engine. Those are not strictly user events, but also, for example, stages of loading (before loading a node, after loading a node, etc...), or checking (the engine is checking for permissions, do you want to add some?).

In reality, hooks are functions that extend drupal functionality, so you add your own behaviors to the drupal-provided ones. Drupal will then call those hooks in the appropriate time, to allow you do perform your actions.

So there is no tight connection with forms or pages, and there is no relation to anything like the MVC model... as of version 6, drupal is not object-based.

This regards the strictly drupal part. Your module is build on top of this, but it may use whatever architecture you wish. It may be object-oriented, and it may use MVC or any other pattern.