Static Interfaces and Initialization in PHP

[josh]

The constructs self::some_static_member_or_function and static::some_static_member_or_function are similar in PHP and can often be used interchangeably. I come across more code using “static” and it is thematic because both related to variables and functions that are declared “static” (only choice). However, they are different, static:: is looser, and, IMO, kind of wild and dangerous.

In a situation where classes B and C are both derived from A, but neither B nor C is derived from the other, static:: allows late binding of calls within B to static objects and data members from C, just in case a chain of function calls descended through C to get to code in B. This in counter-intuitive from an OOP POV. There is no real way to prevent it happening by accident either. So it is better to use self:: by default and only use static:: where it is actually required for late binding, taking care to check for potential name collisions in even unrelated classes implementing static variables or methods with the same names.

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