gh-129911: pygettext: Fix the keyword entry in help output

[tomasr8]

This simply replaces the interpolated value %(DEFAULTKEYWORDS)s with the list of default keywords.
The default keywords are unlikely to change often so there is no advantage to keeping the help text parametrized.

• Issue: pygettext: help output for keywords prints the whole keyword dictionary #129911

[StanFromIreland]

Why hard code them? We can just get the keywords from the dictionary.

__doc__ = __doc__ % {"DEFAULTKEYWORDS": ", ".join(DEFAULTKEYWORDS.keys())}

--- pygettext.py	2025-02-09 21:26:04.337335656 +0000
+++ pygettext-proposed.py	2025-02-09 21:27:36.552807306 +0000
@@ -171,7 +171,7 @@
 
 
 def usage(code, msg=''):
-    print(__doc__ % globals(), file=sys.stderr)
+    print(__doc__, file=sys.stderr)
     if msg:
         print(msg, file=sys.stderr)
     sys.exit(code)
@@ -295,6 +295,7 @@
     'dnpgettext': {1: 'msgctxt', 2: 'msgid', 3: 'msgid_plural'},
 }
 
+__doc__ = __doc__ % {"DEFAULTKEYWORDS": ", ".join(DEFAULTKEYWORDS.keys())}
 
 def matches_spec(message, spec):
     """Check if a message has all the keys defined by the keyword spec."""

[tomasr8]

Why hard code them?

Good question! Several reasons:

• The default keyword list is not going to change anytime soon, so we don't gain much by keeping it dynamic.
• Having to format a module string feels like a strange pattern so I prefer to avoid it and rather keep it simple.
• If the default keyword format changes again (which is more likely than adding a new default keyword), we might get some ugly output and we'll have to fix the help text yet again (same reason for this PR existing).

[StanFromIreland]

Good enough explanation for me

[tomasr8]

I only test that the --help argument works, not that the help text matches a snapshot exactly, though I can add it

[tomasr8]

@AA-Turner is it ok if I request your review on PRs related to pygettext? I don't want to create too much noise if you'd prefer not to 🙂

[serhiy-storchaka]

LGTM.

[serhiy-storchaka]

Note also the output of ./python -m pydoc Tools/i18n/pygettext.py.

Using __doc__ as the help in getopt-based scripts is a nice trick. But there are issues with dynamically generated help and localization. Hardcoding the list of names looks acceptable in this context.