Codeigniter hooks

Anybody knows reasonable hooks usage? I wrote 2 projects and have no idea wh开发者_如何学Pythonat the used for.

Thanks

---

Hooks in CodeIgniter are used to extend or override the core functionality -- for example:

EXTEND:
If you want to add some basic analytics to your page you might add a pre_system and a post_system hook to log the length of time the request took (or at least, how long CodeIgniter took to process the request) and to record the requested URL, the user, and the time. (The first part of this hook series could be handled better by the Benchmark class, since it is already loaded).

OVERRIDE:
From the documentation:

cache_override Enables you to call your own function instead of the _display_cache() function in the output class. This permits you to use your own cache display mechanism.

---

From CodeIgniter User Guide Version 2.1.4

CodeIgniter's Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files. When CodeIgniter runs it follows a specific execution process, diagramed in the Application Flow page. There may be instances, however, where you'd like to cause some action to take place at a particular stage in the execution process. For example, you might want to run a script right before your controllers get loaded, or right after, or you might want to trigger one of your own scripts in some other location.

Not sure what you consider "reasonable" though, but the above summarizes it pretty well. They allow you to add additional behavior to core library classes at various points in the execution cycle.