[Python-Dev] Classes and Metaclasses in Smalltalk (original) (raw)

Thomas Heller thomas.heller@ion-tof.com
Wed, 2 May 2001 15:12:40 +0200

[Greg Ward]

On 02 May 2001, Guido van Rossum said: > Yes, I can see how to write super() using current tools (or 1.5.2 > even). The problem is that this makes super calls even more wordy > than they already are! I can't think of anything that wouldn't > require compiler support though.

I was just doing some gedanken with various ways to spell "super", and I think my favourite is the same as Java's (as I remember it): class MyClass (BaseClass): def foo (self, arg1, arg2): super.foo(arg1, arg2)

Since I don't know much about Python's guts, I can't say how implementable this is, but I like the spelling. The semantics would be something like this (with adjustments to the reality of Python's guts): * 'super' is a magic object that only makes sense inside a 'def' inside a 'class' (at least for now; perhaps it could be generalized to work at class scope as well as method scope, but let's keep it simple) * super's notional getattr() does something like this: - peek at the calling stack frame and fetch the calling function (MyClass.foo) and the first argument to that function (self) - [is this possible?] ensure that callingfunction is a bound method, and that it's bound to the self object we just plucked from the stack; raise a "misuse of super object" exception if not - walk the superclass tree starting at self.class.bases Caareful! The search in the above context must start at MyClass.bases which may not be the same as self.class.bases.

Thomas