| Alan Isaac wrote: | > "Terry Reedy" <[EMAIL PROTECTED]> wrote in message | > news:[EMAIL PROTECTED] | > | >> Should be in the reference manual section on comparisons.
| > Only to this extent: | > http://www.python.org/doc/2.4/ref/comparisons.html | > | > objects of different types always compare unequal, and are ordered | > consistently but arbitrarily. This is the sentence I was referring to. The key word is 'arbitrary', meaning withoug any particular reason why, as in "why does None compare as it does?" | > (This unusual definition of comparison was used to simplify the | > definition of operations like sorting That was broken when complex numbers were added. | > In the future, the comparison rules for objects of different types are | > likely to change.) Will change in 3.0. | > ... Most other types compare unequal unless they are the same object; | > the choice whether one object is considered smaller or larger than | > another one is made arbitrarily but consistently within one execution | > of a program. | > | > This does not provide a direct answer to "why" None comparisons. Yes it does. There is no 'why'! | > (As far as I can tell, None is less than any object.) This is an artifact of the current CPython implementation. | > However, Gary Herron's explanation makes sense: this provides a stable | > sort when None is involved, and meets the criterion that objects of | > different types must always compare unequal. However this would also | > be true if None always compared greater than any object, and the current | > behavior does not seem to be guaranteed. >From the viewpoint of the language, the current behavior is an arbitrary artifact. But here, I suspect, is the implementation why. CPython compares mixed objects by type object address. It is *currently* written and compiled so that NoneType has the lowest address among type objects. Terry Jan Reedy -- http://mail.python.org/mailman/listinfo/python-list
