[Python-Dev] defaultdict proposal round three (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Tue Feb 21 10:50:17 CET 2006

Delaney, Timothy (Tim) wrote:

However, because Python uses duck typing, I tend to feel that subclasses in Python should be drop-in replacements.

Duck-typing means that the only reliable way to assess whether two types are sufficiently compatible for some purpose is to consult the documentation -- you can't just look at the base class list.

I think this should work both ways. It should be okay to not document autodict as being a subclass of dict, even if it happens to be implemented that way.

I've adopted a convention like this in PyGUI, where I document the classes in terms of a conceptual interface hierarchy, without promising that they will be implemented that way.

Greg

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