Why use interfaces in PHP (OOP)

[dpacmittal]

I am learning OOP in PHP and its been a pretty good learning experience so far. What I didn't understand at all is interfaces. I understand the implications of multiple inheritance, and interface is used just to solve that. But what's the use?

If we have to define the function in derived class why use interface, why not directly declare and define it inside the derived class?

Am I missing something or is it really useless?

[Alex]

As with many standards in programming (especially with OOP) interfaces aren't totally for you, they're for other programmers that might use your code. It's a good way to insure that an object will maintain certain methods.

[dpacmittal]

As with many standards in programming (especially with OOP) interfaces aren't totally for you, they're for other programmers that might use your code. It's a good way to insure that an object will maintain certain methods.

Not so important then, eh?

[Alex]

Definitely not one of the most useful features in PHP, but it can come in handy sometimes, especially when you plan on distributing your code.