[issue28742] argparse.ArgumentDefaultsHelpFormatter sometimes provides inaccurate documentation of defaults, so they should be overrideable

[Peter Eckersley]

Peter Eckersley added the comment:

One thing I noticed when testing my patch by vendorizing it into the Certbot tree was that if a developer had somehow inherited from a version of argparse.Action that *doesn't* have this patch applied to it, and then passes in instances of those inheriting classes to the new patched version, things will break (because the argparse engine now assumes every action has a help_default attribute, rather than checking for it).

That's an unlikely situation but might arise if a developer had managed to use the standard library version of argparse in some places, and the pypi packaged version in other places.

It might be possible, but uglier, to write this patch more defensively so that that wouldn't happen; I would appreciate some feedback on whether people think that's necessary or a good idea.

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components: +Library (Lib)
type:  -> enhancement

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<http://bugs.python.org/issue28742>
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