Łukasz Langa added the comment: No, the suggestion is to only adopt the first part of the patch from 2010, which is to revert KeyError to behave like LookupError again:
>>> print(LookupError('key')) key >>> print(KeyError('key'), 'now') 'key' now >>> print(KeyError('key'), 'in 3.6') key in 3.6 In other words, there is no descriptive message while stringifying KeyError. Having an API with two arguments was disruptive because it moved the key from e.args[0] to e.args[1]. Raymond, would it be acceptable to create a two-argument form where the *second* argument is the message? That way we could make descriptive error messages for dicts, sets, etc. possible. In this world: >>> print(KeyError('key', 'key {!r} not found in dict'), 'in 3.6') key 'key' not found in dict in 3.6 Do you think any code depends on `str(e) == str(e.args[0])`? ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue2651> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com