馃悰 fix: render option metavars, nargs and choices like usage - #353
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The option line assembled its own metavar text from dest and metavar: a user metavar was upper-cased, nargs and choices were ignored, and a positional with a tuple metavar showed only the first element. Usage on the same page showed the correct spec, so the two disagreed. Ask argparse's HelpFormatter._format_args for the text instead; it is the same call that builds the usage line. Positionals join a tuple metavar with spaces, as the name also serves as the reference anchor.
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The option line built its own argument spec from
destandmetavar, and that spec disagreed with the usage line argparse prints two lines above it. 馃悰 A user metavar such as<file>orpath/to/dircame out upper-cased.nargs=2showed oneTWOwhere usage showsTWO TWO;nargs="?","*"andREMAINDERcollapsed to a bare name;choiceswere missing; a positional withmetavar=("SRC", "DST")showed onlySRC.Options now hand the action to argparse's own
HelpFormatter._format_args, the same call that produces the usage line. The literal after the option name therefore reads[OPT],[MANY ...],TWO TWO,...,{json,xml}or the metavar as the author typed it. Positionals join a tuple metavar with spaces for both the displayed name and the anchor; otherwise they keep the metavar ordest, since that name doubles as the reference target.Rendered output changes for parsers that pass a lower-case metavar.
--outdir out_dirused to render asOUT_DIRand now renders asout_dir, matching usage. Option anchors stay the same; a positional with a tuple metavar moves from#tool-SRCto#tool-SRC-DST.