On Fri, 7 Jul 2017 06:05 pm, Gregory Ewing wrote: > Steve D'Aprano wrote: >> In practice, identity is hardly important in Python, except for a few limited >> cases, and the prohibition against using `is` when you mean `==`. > > On the contrary, it's a very important concept needed to make > sense of the way things behave when mutation is involved. > > Witness e.g. the classic newbie mistake of using [[0]*5]*5 > to create a matrix of zeroes. I don't know how to explain > why that goes wrong without using the phrase "same object" > in some way.
That would be one of the few limited cases I mentioned :-) I'll grant you that having the concept of "the same object" can be important. -- Steve “Cheer up,” they said, “things could be worse.” So I cheered up, and sure enough, things got worse. -- https://mail.python.org/mailman/listinfo/python-list
