[Python-Dev] defaultdict proposal round three (original) (raw)
Delaney, Timothy (Tim) tdelaney at avaya.com
Tue Feb 21 01:19:24 CET 2006
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Greg Ewing wrote:
In other words, just because A inherits from B in Python isn't meant to imply that an A is a drop-in replacement for a B.
Hmm - this is interesting. I'm not arguing Liskov violations or anything ...
However, because Python uses duck typing, I tend to feel that subclasses in Python should be drop-in replacements. If it's not a drop-in replacement, then it should probably not subclass, but just use duck typing (probably by wrapping).
Subclassing implies a stronger relationship to me. Which is why I think I prefer using a wrapper for a default dict, rather than a subclass.
Tim Delaney
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