On Sun, Aug 21, 2016 at 5:27 AM, Chris Angelico <ros...@gmail.com> wrote: > Hmm. It would somehow need to be recognized as "not iterable". I'm not > sure how this detection is done; is it based on the presence/absence > of __iter__, or is it by calling that method and seeing what comes > back? If the latter, then sure, an __iter__ that raises would cover > that.
PyObject_GetIter calls __iter__ (i.e. tp_iter) if it's defined. To get a TypeError, __iter__ can return an object that's not an iterator, i.e. an object that doesn't have a __next__ method (i.e. tp_iternext). For example: >>> class C: ... def __iter__(self): return self ... def __getitem__(self, index): return 42 ... >>> iter(C()) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: iter() returned non-iterator of type 'C' If __iter__ isn't defined but __getitem__ is defined, then PySeqIter_New is called to get a sequence iterator. >>> class D: ... def __getitem__(self, index): return 42 ... >>> it = iter(D()) >>> type(it) <class 'iterator'> >>> next(it) 42 _______________________________________________ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct: http://python.org/psf/codeofconduct/