From bdc9c55c460509c4755bb4983b40b876b1ed2610 Mon Sep 17 00:00:00 2001 From: Hans Then Date: Wed, 17 Sep 2025 17:25:17 +0200 Subject: [PATCH] gh-132558: Improve `argparse` docs on combining `type` and `choices` (GH-133827) (cherry picked from commit dd0840bf67e194ab64f340b8a7fbda24cb25e177) Co-authored-by: Hans Then Co-authored-by: Savannah Bailey --- Doc/library/argparse.rst | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst index 6d9348c547227d..1ca4ff87c3fd1d 100644 --- a/Doc/library/argparse.rst +++ b/Doc/library/argparse.rst @@ -1058,16 +1058,21 @@ if the argument was not one of the acceptable values:: game.py: error: argument move: invalid choice: 'fire' (choose from 'rock', 'paper', 'scissors') -Note that inclusion in the *choices* sequence is checked after any type_ -conversions have been performed, so the type of the objects in the *choices* -sequence should match the type_ specified. - Any sequence can be passed as the *choices* value, so :class:`list` objects, :class:`tuple` objects, and custom sequences are all supported. Use of :class:`enum.Enum` is not recommended because it is difficult to control its appearance in usage, help, and error messages. +Note that *choices* are checked after any type_ +conversions have been performed, so objects in *choices* +should match the type_ specified. This can make *choices* +appear unfamiliar in usage, help, or error messages. + +To keep *choices* user-friendly, consider a custom type wrapper that +converts and formats values, or omit type_ and handle conversion in +your application code. + Formatted choices override the default *metavar* which is normally derived from *dest*. This is usually what you want because the user never sees the *dest* parameter. If this display isn't desirable (perhaps because there are