[Python-Dev] PEP 246, redux (original) (raw)

Paul Moore p.f.moore at gmail.com
Wed Jan 12 14:44:50 CET 2005

On Wed, 12 Jan 2005 00:33:22 +0100, Alex Martelli <aleax at aleax.it> wrote:

But adaptation is not transmission! It's PERFECTLY acceptable for an adapter to facade: to show LESS information in the adapted object than was in the original. It's PERFECTLY acceptable for an adapter to say "this piece information is not known" when it's adapting an object for which that information, indeed, is not known. It's only CONJOINING the two perfectly acceptable adapters, as transitivity by adapter chain would do automatically, that you end up with a situation that is pragmatically undesirable: asserting that some piece of information is not known, when the information IS indeed available -- just not by the route automatically taken by the transitivity-system.

[Risking putting my head above the parapet here :-)]

If you have adaptations A->B, B->C, and A->C, I would assume that the system would automatically use the direct A->C route rather than A->B->C. I understand that this is what PyProtocols does.

Are you mistakenly thinking that shortest-possible-route semantics aren't used? Maybe the PEP should explicitly require such semantics.

If I'm missing the point here, I apologise. But I get the feeling that something's getting lost in the discussions.

Paul.

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