PHP and Static Variables in Object Member Functions

Question

Up until today, I thought I had a fairly good grasp of how the static modifier worked. I know that (in laymans terms) a static variable in a function does not \'reset\' acro

Answer 1

As far as I know, all languages with static variables treat them this way. Think of static variables as global variables that can only be accessed from a certain scope.

Answer 2

I've copied the following information from this article by Josh Duck: http://joshduck.com/blog/2010/03/19/exploring-phps-static-scoping/

Static variables have been available since PHP 4 and allow you to define a persistent variable that is only accessible from the current function. This allows you to encapsulate state into a function or method and can eliminate the need for classes where a single function will suffice.

When a static variable is defined inside a class method they will always refer to the class on which the method was called. In doing this they act almost like properties referenced through static, though there are subtle differences.

Static variables can’t preserve the calling class scope. This can be potentially problematic if you have an inherited method containing a static variable that is called from both inside and outside its class.

Answer 3

1. This is expected.
2. This is also the case in C++ (and probably others as well).

You should think of non-static class member functions as if they were just like ordinary functions, but with an implicit $this argument that is automatically provided by the interpreter. (That's exactly how they're implemented in most languages.)