Ezio Melotti added the comment: While this is documented for isinstance, I'm not sure it should be advertised too much, as it seems to me an implementation detail and doesn't seem too useful in practice.
This is a side-effect of the fact that isinstance(x, (A, B, ...)) is equivalent to isinstance(x, A) or isinstance(x, B) or ... and therefore isinstance(x, (A, (B, C))) is equivalent to isinstance(x, A) or isinstance(x, (B, C)) which in turn is equivalent to isinstance(x, A) or (isinstance(x, B) or isinstance(x, C)) While this behavior seems intentional [0], it doesn't seem to be tested [1]. FTR this is supported by PyPy too. [0]: http://hg.python.org/cpython/file/default/Objects/abstract.c#l2494 [1]: http://hg.python.org/cpython/file/default/Lib/test/test_builtin.py#l704 ---------- nosy: +ezio.melotti type: -> enhancement _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue16437> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
