Nick Maclaren schrieb: >> If so, they just shouldn't use the equal operator (==). == ought to >> be transitive. It should be consistent with has(). > > Fine. A very valid viewpoint. Would you like to explain that to > the IEEE 754 people?
Why should I? I don't talk about IEEE 754, I talk about Python. > Strictly, it is only the reflexive property that IEEE 754 and the > Decimal module lack. Yes, A == A is False, if A is a NaN. But > the definition of 'transitive' often requires 'reflexive'. I deliberately stated 'transitive', not 'reflexive'. The standard definition of 'transitive' is "if a==b and b==c then a==c". > The most common form was where comparison was equivalent to subtraction, > and there were numbers such that A-B == 0, B-C == 0 but A-C != 0. That > could occur even for integers on some systems. I don't THINK that the > Decimal specification has reintroduced this, but am not quite sure. I'm not talking about subtraction, either. I'm talking about == and hash. > Fine. Again, a very valid viewpoint. Would you like to explain it > to the IEEE 754, Decimal and C99 people, and the Python people who > think that tracking C is a good idea? I'm not explaining anything. I'm stating an opinion. > This one is NOT going to go away, and is going to get more serious, > especially if extended floating-point formats like Decimal take off. > Note that it is not a fault in Decimal, but a feature of almost all > extended floating-points. As I said, I have no answer to it. It doesn't look like you *need* to give an answer now. I thought you were proposing some change to Python (although I'm uncertain what that change could have been). If you are merely explaining things (to whom?), just keep going. Regards, Martin _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
