Steven Bethard <steven.beth...@gmail.com> added the comment:
I'm sympathetic to the idea that '-' should be translated similarly for
optional and positional arguments, but as you've noted, it would be a risky
patch because it's already possible for people to use getattr on hyphenated
arguments. So I think this isn't possible without a long deprecation process
first.
> But patching the module to allow explicitly setting dest via keyword
> argument shouldn't hurt anybody.
I agree that it wouldn't hurt anybody. If you can find a way to do this, feel
free to provide a patch.
However, the correct way to have one name for the attribute (i.e. dest=) and
one name for the help (i.e. metavar=) is to use the metavar argument like so:
parser.add_argument('positional_args', metavar='positional-args')
That said, this is not the first time I've seen someone run into this problem.
I think the documentation could be improved in a few ways:
(1) In the "name or flags" section, describe how the flags (for optional
arguments) are translated into both a default "dest" (stripping initial '-' and
converting '-' to '_') and into a default "metavar" (stripping initial '-' and
uppercasing). Part of this is in the "dest" and "metavar" documentation, but
probably belongs up in the "name or flags" documentation. Add cross-references
to "dest" and "metavar" sections.
(2) In the "name or flags" section, describe how the name (for positional
arguments) are translated into the same default "dest" and "metavar" (no string
munging at all). Again, move stuff from the "dest" and "metavar" sections as
necessary. Add cross-references to "dest" and "metavar" sections.
(3) In the "dest" section and somewhere in the "parse_args" section, describe
how "getattr" can be used to get attributes whose names aren't valid Python
identifiers. Maybe cross-reference this section from the edits in (2).
----------
assignee: -> docs@python
components: +Documentation
nosy: +docs@python
versions: +Python 3.4
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