https://github.com/python/cpython/commit/da8673da362a2135cd621ac619d3aced6bb55100
commit: da8673da362a2135cd621ac619d3aced6bb55100
branch: main
author: Serhiy Storchaka <[email protected]>
committer: serhiy-storchaka <[email protected]>
date: 2024-10-25T08:41:38Z
summary:
gh-84545: Clarify the 'extend' action documentation in argparse (GH-125870)
files:
M Doc/library/argparse.rst
diff --git a/Doc/library/argparse.rst b/Doc/library/argparse.rst
index 65663d43f50a9d..940698218534e0 100644
--- a/Doc/library/argparse.rst
+++ b/Doc/library/argparse.rst
@@ -741,6 +741,21 @@ how the command-line arguments should be handled. The
supplied actions are:
>>> parser.parse_args('--str --int'.split())
Namespace(types=[<class 'str'>, <class 'int'>])
+* ``'extend'`` - This stores a list and appends each item from the multi-value
+ argument list to it.
+ The ``'extend'`` action is typically used with the nargs_ keyword argument
+ value ``'+'`` or ``'*'``.
+ Note that when nargs_ is ``None`` (the default) or ``'?'``, each
+ character of the argument string will be appended to the list.
+ Example usage::
+
+ >>> parser = argparse.ArgumentParser()
+ >>> parser.add_argument("--foo", action="extend", nargs="+", type=str)
+ >>> parser.parse_args(["--foo", "f1", "--foo", "f2", "f3", "f4"])
+ Namespace(foo=['f1', 'f2', 'f3', 'f4'])
+
+ .. versionadded:: 3.8
+
* ``'count'`` - This counts the number of times a keyword argument occurs. For
example, this is useful for increasing verbosity levels::
@@ -766,17 +781,6 @@ how the command-line arguments should be handled. The
supplied actions are:
>>> parser.parse_args(['--version'])
PROG 2.0
-* ``'extend'`` - This stores a list, and extends each argument value to the
- list.
- Example usage::
-
- >>> parser = argparse.ArgumentParser()
- >>> parser.add_argument("--foo", action="extend", nargs="+", type=str)
- >>> parser.parse_args(["--foo", "f1", "--foo", "f2", "f3", "f4"])
- Namespace(foo=['f1', 'f2', 'f3', 'f4'])
-
- .. versionadded:: 3.8
-
Only actions that consume command-line arguments (e.g. ``'store'``,
``'append'`` or ``'extend'``) can be used with positional arguments.
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