Mark Dickinson added the comment: > could you point me to where this logic is implemented in CPython's source?
Most of the relevant code is in Objects/abstract.c and Objects/typeobject.c. A BINARY_ADD opcode (for example) ends up calling PyNumber_Add: https://github.com/python/cpython/blob/v3.6.1/Objects/abstract.c#L913 which in turn calls binary_op1, where you see an explicit check for the nb_add slots of the two operands being identical: https://github.com/python/cpython/blob/v3.6.1/Objects/abstract.c#L769-L770 For a user-defined class, the slots themselves are defined in typeobject.c. Here's where nb_add is defined: https://github.com/python/cpython/blob/v3.6.1/Objects/typeobject.c#L5952 and here's the explicit check for overloading in the SLOT1BIN macro definition: https://github.com/python/cpython/blob/v3.6.1/Objects/typeobject.c#L5796 There's also an explicit test for the arithmetic operation behaviour in Lib/test/test_descr.py. In short, I doubt this was ever a bug: everything points to this being a deliberate design decision. I hope someone on python-ideas can elaborate on the rationale behind that design decision (and also on why that rationale doesn't apply to comparisons). In contrast, it does seem plausible to me that the *comparison* failure to check for an explicit override may have been accidental. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue30140> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com