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phptraitstype-hinting

PHP type-hinting traits

I have a trait. For the sake of creativity, let's call this trait Trait:

trait Trait{    
    static function treat($instance){    
        // treat that trait instance with care
    }
}

Now, I also have a class that uses this trait, User. When trying to call treat with an instance of User, everything works. But I would like to type-hint that only instances of classes using Trait should be given as arguments, like that:

static function treat(Trait $instance){...}

Sadly, though, this results in a fatal error that says the function was expecting an instance of Trait, but an instance of User was given. That type of type-hinting works perfectly for inheritance and implementation, but how do I type-hint a trait?

Solution

  • You can't as DaveRandom says. And you shouldn't. You probably want to implement an interface and typehint on that. You can then implement that interface using a trait.