paul j3 added the comment: This is a straight forward patch, modifying '_registry_get' to return 'default' if it gets this 'TypeError'. 'test_argparse.py' has a testcase based on jnothman's example. Temporarily it includes a skipped test that would pass the original code.
The alternative would be to add a note to the documentation to the effect that the 'type' must also be hashable. But for an edge condition like this, that may be more confusing than enlightening. While 'dict(one=1, two=20).get' now works as a 'type' callable, it is not ideal. If there is no match it returns None. The alternative '.__getitem__' raises a KeyError. But '_get_values' handles TypeError and ValueErrors, the kinds returned by 'int' and 'float'. It also handles an ArgumentTypeError, giving a custom type more control over the error message. Is it worth noting something about the type errors in the documentation? I've seen users make a different error with the type parameter - 'type=boolean', thinking this means the input should be converted to boolean. They are thinking of 'type' as a datatype, rather than a function that converts a string into something else. I don't know of a solution other than explaining that 'boolean()' does not act like 'int()'. This patch also handles the 'action' case. However I can't think of a way write a Action subclass that would be unhashable. It would have to inherit from both Action and dict. ---------- keywords: +patch Added file: http://bugs.python.org/file35936/patch.diff _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue16516> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
