Message 188869 - Python tracker (original) (raw)

'parse_fallback_args()' function is only in the 'test_intermixed.py' file, not the patch. It should be in the 'if name' section of that file, along with the modified 'exit()' method, since it is part of these testing suit, not meant to be imported. 'test_intermixed.py' is more of an example and discussion tool, not a formal test.

I added the '_fallback' optional argument because the normal exit from 'parse_args' using SystemExit is remarkably uninformative. It's hard to distinguish between the 'fallback' errors, and the ones generated by 'parse_known_args' (that have more to do with the argument strings). One is a programming error, the other a user generated error.

It is possible to redefine ArgumentParser.error() so it gives more information, for example by raising an Exception(message). I have added to test_intermixed.py an alternative 'parse_fallback_args' that uses such a modified error rather than the _fallback option. But that ends up modifying the normal parsing error generation as well.

I used the 'fallback' idea to test 'parse_intermixed_args' against the whole set 'test_argparse.py' tests. It would nice to have a way of doing that automatically anytime other features are added to 'parse_args'. But I can't think of a clean way of doing that.

Regarding earlier versions of these files - I do not see a way of deleting them.

I have attached a modified test_intermixed.py that has these changes. I also modified how 'parse_known_intermixed_args' restores the original value of self.usage, using an outer 'try:finally:' block. I need to make a note to myself to put that in the patch.