Should a function be used in both static and object context

Question

In my company's codebase, i see functions used in both static and object context. For e.g. a class A has a function b() which is called both using A::b() and/or object_of_type_A->b(). I know this throws an error if strict is turned on. But I wanted to know if this is a bad practice and if yes, then why? Thanks for any answers.

Let me know if I don't make sense anywhere. I would be happy to clarify.

Answer 1

Here's some test code:

<?php

error_reporting(E_ALL | E_STRICT);

class Foo{
    public function a(){
    }
    public static function b(){
    }
}

$MyFoo = new Foo;
Foo::a(); // Strict Standards: Non-static method Foo::a() should not be called statically
Foo::b();
$MyFoo->a();
$MyFoo->b(); // No complaints

?>

PHP/5.3 warns about static calls to non-static methods, which is fine since they are subject to failure as soon as you want to access $this. But it does not complain about object context calls to static functions: there's nothing that can go wrong. This behaviour is documented:

Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. A property declared as static can not be accessed with an instantiated class object (though a static method can) [...] Because static methods are callable without an instance of the object created, the pseudo-variable $this is not available inside the method declared as static.

So, as far as PHP is concerned, what you found in the code base is not wrong. However, I think it's slightly confusing.