PHP instanceof for traits

Question

What is the proper way to check if a class uses a certain trait?

Answer 1

While nothing stops you from using instanceof with traits, the recommended approach is to pair traits with interfaces. So you'd have:

class Foo implements MyInterface
{
    use MyTrait;
}

Where MyTrait is an implementation of MyInterface. Then you check for the interface instead of traits like so:

if ($foo instanceof MyInterface) {
    ...
}

And you can also type hint, which you can't with traits:

function bar(MyInterface $foo) {
    ...
}

In case you absolutely need to know whether a class is using a certain trait or implementation, you can just add another method to the interface, which returns a different value based on the implementation.