New submission from Douglas Raillard <douglas.raill...@arm.com>:
Re-raising the bug reported by Kevin Shweh: thread: https://bugs.python.org/issue14385 message: https://bugs.python.org/msg337245 Here is a copy for easier reference: The patch for this issue changed LOAD_GLOBAL to use PyObject_GetItem when globals() is a dict subclass, but LOAD_NAME, STORE_GLOBAL, and DELETE_GLOBAL weren't changed. (LOAD_NAME uses PyObject_GetItem for builtins now, but not for globals.) This means that global lookup doesn't respect overridden __getitem__ inside a class statement (unless you explicitly declare the name global with a global statement, in which case LOAD_GLOBAL gets used instead of LOAD_NAME). I don't have a strong opinion on whether STORE_GLOBAL or DELETE_GLOBAL should respect overridden __setitem__ or __delitem__, but the inconsistency between LOAD_GLOBAL and LOAD_NAME seems like a bug that should be fixed. For reference, in the following code, the first 3 exec calls successfully print 5, and the last exec call fails, due to the LOAD_GLOBAL/LOAD_NAME inconsistency: class Foo(dict): def __getitem__(self, index): return 5 if index == 'y' else super().__getitem__(index) exec('print(y)', Foo()) exec('global y; print(y)', Foo()) exec(''' class UsesLOAD_NAME: global y print(y)''', Foo()) exec(''' class UsesLOAD_NAME: print(y)''', Foo()) I encountered the same issue when trying to create a way to "instantiate" modules with some globals replaced by user-defined values to make a dependency-injection system. I therefore want to lookup some names in a separate dict rather than getting the value normally bound in that module (typically by an import statement). ---------- components: Interpreter Core messages: 398299 nosy: douglas-raillard-arm priority: normal severity: normal status: open title: LOAD_NAME not using PyObject_GetItem when globals() is a dict subclass versions: Python 3.10 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue44749> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
