How to modularize a plugin/extension feature for a php app?

Question

I'm working on a task management application for use at my company. Part of the spec is to create a plugin system that lets users customize and extend the functionality as they need, or as their department requires. I'd love to do this in a really elegant and modularized way, but I'm having a hard time figuring out how.

Consider a view that's a task list: each iteration of the generating loop adds a pre_task() and post_task() call on either end, which builds the interactive pieces on either end of the task title (Complete checkbox, comments link, etc). Now, when the system detects and includes the plugin file plugin_time_tracking.php, the plugin should add functionality to post_task() - adding a "track time" button in addition to everything else.

What I'd like to accomplish is making the plugin "hook" onto pre_task() or post_task() - let it do all the legwork by attaching itself to the proper functions and extending them, instead of having the core sort plugins and herd their functions to the right places. Does PHP offer such functionality? Am I going about this the wrong way? Let me know if I need to clarify at all - thanks for the help!

Answer 1

I think you should really use a framework that has a built in plugin infrastructure with capabilities to override/inherit. As an example, let's say Symfony2: in sf2 you could create FormType classes that build the form objects (which then pass certain data tot he view). So in this case to add fields another team would simply need to extend your FormType and modify the build to add new fields. Further the Form Api supports embedding subforms so if they want time track then then just need to embed that in the task form or "turn it on" through whatever configuration facilities you supply.

Similarly with render things, you can define override the view template simply by providing at a different level or referencing a different Bundle (a plugin of sorts).

Now Symfony2 is very complex and it has a high learning curve so it may or my not be the framework you should choose, but something along these lines would be more than appropriate. The WP/Drupal pattern of "hook" functions is incredibly annoying to work with, especially if they are building HTML strings on a deeper layer and not giving you the raw data to output as you see fit.

Answer 2

The boys of Qafoo gave a talk about modularity on the 2012 edition of the PHPBenelux conference. They presented various options to create modular applications such as hooks, patching and inheritance.

You could check out the slides of that presentation here.