[Python-3000] bytes and dicts (was: PEP 3137: Immutable Bytesand Mutable Buffer) (original) (raw)

Terry Reedy tjreedy at udel.edu
Sat Sep 29 04:27:29 CEST 2007

"Guido van Rossum" <guido at python.org> wrote in message news:ca471dc20709281140q2ef95c2ap8bbc7b7d3d46ebc0 at mail.gmail.com... || Well, if we wanted "x" and b"x" to compare unequal instead of raising | an exception, we could just define it that way (it was that way until | just before 3.0a1). But we're explicitly defining it to raise a | TypeError so as to catch buggy code. I think trying to fix dict lookup | so that it, and only it, treats this as unequal, would be adding too | many quirks. || We could choose to kill the TypeError altogether. If we keep it, we | should consistently let it raise TypeError everywhere. || The question is whether it's worth the effort to raise TypeError when | the potential exists that a certain hash sequence could raise this | TypeError. I'm less and less convinced -- after all, we're making the | exception only for bytes/str, not for other types that might raise | TypeError upon comparison. || So, I think that after all this was a bad idea. Sorry.

If you mean making a special case exception for string/bytes equality test, I agree. Would a restricted key dict (say, rdict, in collections) solve the problem you are aiming at?

import collections adict = rdict(str) bdict = rdict(bytes)

Now any buggy insertions get caught.

Terry J. Reedy

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