[issue9348] Calling argparse's add_argument with the wrong number of metavars causes delayed error message

[daniel hahler]

daniel hahler <python-bugs at thequod.de> added the comment:

This adds overhead, since it creates a formatter and uses it for formatting only for validation purposes.

I think it is better to only have the error when the formatter is actually used (i.e. the help is displayed - which is not the typical use case, and it should be optimized for not displaying the help (i.e. only parsing args)).
The error could be more specific than before/initially though, of course.

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nosy: +blueyed

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<https://bugs.python.org/issue9348>
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