[Python-Dev] Dicts are broken Was: unicode hell/mixing str andunicode asdictionarykeys (original) (raw)

Giovanni Bajo rasky at develer.com
Sat Aug 5 13:17:18 CEST 2006

Bob Ippolito <bob at redivi.com> wrote:

Well it's not recomended to mix strings and unicode in the dictionaries but if we mix for example integer and float we have the same thing. It doesn't raise exception but still it is not expected behavior for me:

d = { 1.0: 10, 2.0: 20 } then if i somewhere later do: d[1] = 100 d[2] = 200 to have here all floats in d.keys(). May be this is not a best example. There is a strong difference. Python is moving towards unifying number types in a way (see the true division issue): the idea is that, all in all, user shouldn't really care what type a number is, as long as he knows it's a number. On the other hand, unicode and str are going to diverge more and more. Well, not really. True division makes int/int return float instead of an int. You really do have to care if you have an int or a float most of the time, they're very different semantically.

Then I'd ask why Python goes through hoops to make sure that hash(1.0) == hash(1), in the first place.

Giovanni Bajo

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