| msg116355 - (view) |
Author: Jason Baker (Jason.Baker) |
Date: 2010-09-13 23:25 |
| This is referring to argparse 1.1 installed under Python 2.6. When I was passing in an nargs flag, I figured that since '+' and '*' are valid options, I should pass in strings. So when I tried passing in the string '1' instead of the integer 1, I got the following error: >>> import argparse >>> parser = argparse.ArgumentParser() >>> parser.add_argument('foo', nargs='1') _StoreAction(option_strings=[], dest='foo', nargs='1', const=None, default=None, type=None, choices=None, help=None, metavar=None) >>> parser.parse_args() Traceback (most recent call last): File "", line 1, in File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 1698, in parse_args File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 1730, in parse_known_args File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 1935, in _parse_known_args File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 1884, in consume_positionals File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 2028, in _match_arguments_partial File "build/bdist.macosx-10.6-universal/egg/argparse.py", line 2169, in _get_nargs_pattern TypeError: can't multiply sequence by non-int of type 'str' Fortunately, I had just added the nargs and knew to correct that. However, if I were to do something like read that value in from a config file and forget to coerce the value from a string to an int, I could see how this could be a giant pain to track down. |
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| msg116357 - (view) |
Author: Ned Deily (ned.deily) *  |
Date: 2010-09-14 00:29 |
| Note, argparse is not part of the Python standard library in 2.6 but the 2.7 and 3.2 versions exhibit the same behavior. |
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| msg186962 - (view) |
Author: Mark Lawrence (BreamoreBoy) * |
Date: 2013-04-15 00:07 |
| The behaviour has changed from that given in . Using Python 3.3.1 on Windows. >>> import argparse >>> parser = argparse.ArgumentParser() >>> parser.add_argument('foo', nargs='1') Traceback (most recent call last): File "c:\python33\lib\argparse.py", line 1322, in add_argument self._get_formatter()._format_args(action, None) File "c:\python33\lib\argparse.py", line 585, in _format_args formats = ['%s' for _ in range(action.nargs)] TypeError: 'str' object cannot be interpreted as an integer During handling of the above exception, another exception occurred: Traceback (most recent call last): File "", line 1, in File "c:\python33\lib\argparse.py", line 1324, in add_argument raise ValueError("length of metavar tuple does not match nargs") ValueError: length of metavar tuple does not match nargs The docs http://docs.python.org/3/library/argparse.html#nargs are clear that nargs is an integer or various types of string so I think this could be closed as already fixed. |
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| msg187132 - (view) |
Author: paul j3 (paul.j3) *  |
Date: 2013-04-17 03:12 |
| It does shift the error from parse_args to add_argument, but the message 'ValueError: length of metavar tuple does not match nargs', indicates that it's a side effect of checking on the tuple form of `metavar`. http://bugs.python.org/issue9348 There is still room for cleaning up these tests. There are 2 functions that define what are acceptable values for nargs, [None, OPTIONAL, ZERO_OR_MORE, ONE_OR_MORE, REMAINDER, PARSER, integer]. Should one or other explicitly check nargs is an integer if it does not match one of the other strings? And the test in _ActionContainer.add_argument() # raise an error if the metavar does not match the type if hasattr(self, "_get_formatter"): try: self._get_formatter()._format_args(action, None) except TypeError: raise ValueError("length of metavar tuple does not match nargs") uses an ArgumentParser._get_formatter method (though 'hasattr' prevents runtime errors). In fact both functions that use nargs belong to the parser, not the container. I wonder if `add_argument` should be moved to ArgumentParser. |
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| msg187166 - (view) |
Author: Mark Lawrence (BreamoreBoy) * |
Date: 2013-04-17 14:26 |
| The first error raised is "TypeError: 'str' object cannot be interpreted as an integer", followed by "ValueError: length of metavar tuple does not match nargs". Therefore the code has already been changed to reflect the title of this issue. If other code changes are needed I believe that should be done in a new or another already existing issue. |
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| msg187614 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2013-04-23 07:16 |
| This nargs test using the formater applies only when the container has a help formatter. That is true for a ArgumentParser, but not for an argument_group. group = parser.add_argument_group('g') group.add_argument('bar', nargs='test') does not raise an error. format_help will produce an error: ... File "./argparse.py", line 585, in _format_args formats = ['%s' for _ in range(action.nargs)] TypeError: 'str' object cannot be interpreted as an integer while parse_args produces the error: ... File "./argparse.py", line 2200, in _get_nargs_pattern nargs_pattern = '(-*%s-*)' % '-*'.join('A' * nargs) TypeError: can't multiply sequence by non-int of type 'str' |
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| msg187686 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2013-04-24 06:22 |
| This patch adds a value test for nargs during add_argument. The core of the new test is in ArgumentParser._check_argument. add_argument() now calls ArgumentParser._check_argument(), which calls _format_args(). If it gets a TypeError, it raises a metavar ValueError as before. But if it gets an ValueError, it raises an ArgumentError. An argument group gets the _check_argument method from its container. This way, check_argument() works for both parsers and groups. HelpFormater _format_args() now raises a ValueError if the nargs is not an integer (or one of the recognized strings). What kind of error should we produce when there is a problem with nargs? An ArgumentError has the advantage that it includes the action name. But the metavar tuple test was coded to raise ValueError. Plus the test_argparse.py TestInvalidArgumentConstructors class tests all check for TypeError or ValueError. I have kept the metavar tuple case as ValueError. That way, test_argparse.py runs without a change. I still need to add tests for invalid string nargs values. And I think the case could be made for returning ArgumentValue errors. |
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| msg187687 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2013-04-24 06:26 |
| The attached test_nargswarn.py file tests the argparse.py patch. It tries out various nargs values, both for parsers, groups, and mutually exclusive groups. I intend to recast these to work in test_argparse.py |
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| msg187754 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2013-04-25 04:31 |
| This is a revision of yesterday's patch. It includes a couple of test cases that check that parser, groups, and exclusive groups all produce the error message. I also changed the metavar tuple case to return an ArgumentError, and changed test_argparse.py accordingly. (this metavar testing was added in http://bugs.python.org/issue9348). This issue overlaps with http://bugs.python.org/issue16970, 'argparse: bad nargs value raises misleading message'. There, though, the focus is more on the error message when nargs=0. While nargs<1 might not make much sense, it technically does not break anything. |
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| msg192719 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2013-07-09 03:16 |
| I included this patch (with minor changes) in a patch that I just posted to http://bugs.python.org/issue16468. That issue deals with the argument choices option, which can be tested along with nargs and metavars. |
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| msg220017 - (view) |
Author: paul j3 (paul.j3) * |
Date: 2014-06-08 06:05 |
| http://bugs.python.org/issue21666 raises the possibility of testing the 'help' parameter in the same way. By adding (to _check_argument): # check the 'help' string try: self._get_formatter()._expand_help(action) except (ValueError, TypeError, KeyError) as e: raise ArgumentError(action, 'badly formed help string') |
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| msg380484 - (view) |
Author: Irit Katriel (iritkatriel) * |
Date: 2020-11-07 00:37 |
| This is fixed now: Python 3.10.0a2+ (heads/bpo-42184:f3cb814315, Nov 7 2020, 00:31:51) [MSC v.1916 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> import argparse >>> parser = argparse.ArgumentParser() >>> parser.add_argument('foo', nargs='1') Traceback (most recent call last): File "", line 1, in File "C:\Users\User\src\cpython\lib\argparse.py", line 1430, in add_argument self._get_formatter()._format_args(action, None) File "C:\Users\User\src\cpython\lib\argparse.py", line 611, in _format_args raise ValueError("invalid nargs value") from None ValueError: invalid nargs value |
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