When to use self over $this?

Question

In PHP 5, what is the difference between using self and $this?

When is each appropriate?

Answer 1

self refers current class(in which it is called),

$this refers current object. You can use static instead of self. See the example:

    class ParentClass {
            function test() {
                    self::which();  // output 'parent'
                    $this->which(); // output 'child'
            }

            function which() {
                    echo 'parent';
            }
    }

    class ChildClass extends ParentClass {
            function which() {
                    echo 'child';
            }
    }

    $obj = new ChildClass();
    $obj->test();

Output: parent child