Late static binding

Wed, 19 Jul 2006 17:23:00 GMT

Update: This has been discussed and will be uh, sort of fixed, in PHP6. You’ll be able to use static::my_method() to get the real reference to self in class methods. Not optimal, but still a solution I guess.

As colder on ##php (freenode) told me today, class methods in PHP don’t have what they call late static binding. What’s that? It means that this code:

class Foo
{
  public static function my_method()
  {
    echo "I'm a " . get_class() . "!\n";
  }
}

class Bar extends Foo
{}

Bar::my_method();

outputs “I’m a Foo!”, instead of “I’m a Bar!”. That’s not fun.

Using __CLASS__ in place of get_class() makes zero difference. You end up with proxy methods in each subclass of Foo that pass in the real name of the calling class, which sucks.

class Bar extends Foo
{
  public static function my_method()
  {
    return parent::my_method( get_class() );
  }
}

I was told that they had a discussion about this on the internal PHP list, so at least they’re thinking about this stuff. Too bad PHP5 doesn’t have it. I guess I should just be glad I won’t be maintaining this code.

The resident PHP coder said “just make your code simpler”, which is what I was trying to do by removing duplication. Too bad that plan sort of backfired. I guess odd things like this are where PHP starts to show that OO was tacked on as an after-thought.