[Python-Dev] PEP 246: lossless and stateless (original) (raw)

Bob Ippolito bob at redivi.com
Fri Jan 14 02:08:43 CET 2005

On Jan 13, 2005, at 20:03, Clark C. Evans wrote:

Ok. I think we have identified two sorts of restrictions on the sorts of adaptations one may want to have:

stateless' the adaptation may only provide a result which_ _does not maintain its own state_ _lossless' the adaptation preserves all information available in the original object, it may not discard state If we determined that these were the 'big-ones', we could possibly allow for the signature of the adapt request to be parameterized with these two designations, with the default to accept any sort of adapter: adapt(object, protocol, alternative = None, stateless = False, lossless = False) conform(self, protocol, stateless, lossless) adapt(self, object, stateless, lossless) Then, Guido's 'Optional Static Typing', def f(X: Y): pass would be equivalent to def f(X): X = adapt(Y, True, True) In other words, while calling adapt directly would allow for any adapter; using the 'Static Typing' short-cut one would be asking for adapters which are both stateless and lossless. Since conform and adapt would sprout two new arguments, it would make those writing adapters think a bit more about the kind of adapter that they are providing. Furthermore, perhaps composite adapters can be automatically generated from 'transitive' adapters (that is, those which are both stateless and lossless). But adaptations which were not stateless and lossless would not be used (by default) in an automatic adapter construction. Your thoughts?

In some cases, such as when you plan to consume the whole thing in one function call, you wouldn't care so much if it's stateless.

-bob

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