Type hinting for any object

Question

I've been working on code that's intended to be used with objects, without really caring what the kind of object is. I wanted to type hint that the method being written expected an object of any type, but ran into some difficulty.

I tried function myFunc (object $obj) and function myFunc (stdClass $obj) but both of these generated errors when I tried to pass objects in:

Catchable fatal error: Argument 1 passed to MyClass::MyFunc() must be an instance of object, instance of ObjectActualClass given

The same happened with stdClass as well

What am I missing? I thought that all classes that didn't explicitly inherit from another class inherited from stdClass, meaning that the base class of every class in PHP would be stdClass. Is this not the case?

Answer 1

stdClass is NOT a base class! PHP classes do not automatically inherit from any class. All classes are standalone, unless they explicitly extend another class. PHP differs from many object-oriented languages in this respect.

Answer 2

The best way to enforce this would be to create a degenerate interface called Object. A degenerate interface means it has no defined methods.

interface Object {     // leave blank  } 

Then in your base classes, you can implement Object.

class SomeBase implements Object {     // your implementation  } 

You can now call your function as you wanted to

function myFunc (Object $obj);  myFunc($someBase); 

If you pass any object which inherits from your Object interface, this type hint will pass. If you pass in an array, int, string etc, the type hint will fail.