On 04/21/2012 09:02 AM, Bernd Nawothnig wrote: > On 2012-04-20, dmitrey wrote: >> I have spent some time searching for a bug in my code, it was due to >> different work of "is" with () and []: >>>>> () is () >> True > You should better not rely on that result. I would consider it to be > an implementation detail. I may be wrong, but would an implementation > that results in > > () is () ==> False > > be correct or is the result True really demanded by the language > specification?
You're correct, the behavior is undefined. An implementation may happen to produce either True or False. >>>>> [] is [] >> False > Same for that. Here I have to disagree. If an implementation reused the list object for two simultaneously-existing instances, it would violate first principles. The distinction is simply that () is immutable, so the implementation *may* choose to reuse the same one. -- DaveA -- http://mail.python.org/mailman/listinfo/python-list
