Issue 906746: int object need more informative error message (original) (raw)

Created on 2004-02-29 03:14 by quiver, last changed 2022-04-11 14:56 by admin. This issue is now closed.

Messages (4)
msg54108 - (view)	Author: George Yoshida (quiver)	Date: 2004-02-29 03:14
When int objects encounter a NotImplementedError, they don't say much about what the problem is and are too unfriendly. Error messages can be more verbose. >>> reduce(int.__add__, (1, 2L)) NotImplemented >>> reduce(int.__add__, (1L, 2)) Traceback (most recent call last): File "", line 1, in ? TypeError: descriptor '__add__' requires a 'int' object but received a 'long'
msg54109 - (view)	Author: Raymond Hettinger (rhettinger) *	Date: 2004-05-21 06:09
Logged In: YES user_id=80475 Unfortunately, there may not be any flexibility here. Instead of being just an error message, NotImplemented is a constant that has meaning to other layers of code. I don't see a way to change this or even attach a more informative error message.
msg54110 - (view)	Author: Armin Rigo (arigo) *	Date: 2004-05-21 16:14
Logged In: YES user_id=4771 What you report are not error messages generated by integers, but part of a general internal mecanism. The golden rule with all __xxx__ special methods is that they should not be called directly. This is especially true for binary methods like __add__ which have pretty complex internal semantics. The expression x+y is not equivalent to x.__add__(y): roughly, althought it first tries x.__add__(y), it checks if this returned NotImplemented and calls y.__radd__(x) if it did. But there are a number of subtle rules and special cases. All special methods are meant to be called by language operators (e.g. x+y, `x`,...); for special usages like reduce(), all operators are also available as built-in functions either directly (e.g. repr) or in the module named 'operator' (e.g. operator.add). Finally, unbound method objects like int.__add__ are not to be used unless one is really aware of what is going on.
msg54111 - (view)	Author: Neil Schemenauer (nascheme) *	Date: 2004-05-21 18:48
Logged In: YES user_id=35752 Armin is completely correct. One more point is that NotImplemented is not the same as NotImplementedError. The name similarity is unfortunate because they really have no relation. I'm marking the the bug as invalid as I don't think there is anything to fix.