Terry J. Reedy added the comment: To me, 'roughly' is wrong. Either the equivalence is exact, or it is completely absent . There is no 'nearly' or 'roughly' about this situation.
This is difference from iterator_class_x(args) being mathematically equivalent to generator_function_y(args) in the sense of yielding *exactly* the same sequence of objects, but being different in the Python sense that type(iterator_class_x) != type(generator_function_y). Note: even in this case, I was once in favor of changing 'equivalent' to 'roughly equivalent' in the itertools doc. I now regret that because 'roughly' could be misunderstood. I think that 'mathematically equivalent' or 'equivalent when iterated' or 'equivalent*' would be better, with an explanatory note at the top. As for this issue, __index__ is a reserved name. https://docs.python.org/3/reference/lexical_analysis.html#reserved-classes-of-identifiers a.__index__ = <whatever> is an unauthorized use of a *reserved* word and the effect of such usage is not and need not be documented. The entry for __*__ does include "*Any* use of __*__ names, in any context, that does not follow explicitly documented use, is subject to breakage without warning." To me, that says that the effect of the reserved-word assignment is undefined. It could be made to raise an exception. To be even clearer, I believe we should explicitly state what I consider implicit: something like "Any such use breaks these manuals, in the sense that it may make statements herein untrue. These manuals assume that reserved names are used as specified." ---------- nosy: +terry.reedy stage: -> needs patch type: -> enhancement versions: -Python 3.3, Python 3.4 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue31042> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
