bpo-29030: Document interaction between *choices* and *metavar*. (GH-23884)

1 files changed, 5 insertions, 0 deletions

diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 1a298cdd2b..4542961d78 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -1152,6 +1152,11 @@ Any container can be passed as the *choices* value, so :class:`list` objects,
 Use of :class:`enum.Enum` is not recommended because it is difficult to
 control its appearance in usage, help, and error messages.
 
+Formatted choices overrides 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
+many choices), just specify an explicit metavar_.
+
 
 required
 ^^^^^^^^