On Tue, Jul 5, 2016 at 9:33 PM, Peter Otten <__pete...@web.de> wrote: > Chris Angelico wrote: > >> On Tue, Jul 5, 2016 at 6:36 PM, Peter Otten <__pete...@web.de> wrote: >>> What will >>> >>> $ cat foo.py >>> import foo >>> class A: pass >>> print(isinstance(foo.A(), A)) >>> $ python -c 'import foo' >>> ... >>> $ python foo.py >>> ... >>> >>> print? >> >> I refuse to play around with isinstance and old-style classes. >> Particularly when circular imports are involved. Run this under Python >> 3 and/or explicitly subclass object, and then I'd consider it. :) > > The intended lesson was that there may be two distinct classes > > __main__.A and foo.A > > Even though not just classes, but every object created in the script is > affected this seems to cause the most subtle bugs. > > Maybe the setup can be simplified or the question rephrased to make this > clearer.
Like I said, change the commands to "python3", or explicitly subclass object "class A(object): pass", and then it'll be using new-style classes. The two distinct classes problem is a very real one, and comes of circular (or not-technically-circular, as in the second case) imports. ChrisA -- https://mail.python.org/mailman/listinfo/python-list
