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[3.6] bpo-15427 Clarify nature of parse_args 'args' argument. (GH-3292) #3325

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Mariatta merged 1 commit into from
Sep 10, 2017
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[3.6] bpo-15427 Clarify nature of parse_args 'args' argument. (GH-3292) #3325

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18 changes: 15 additions & 3 deletions Doc/library/argparse.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -898,6 +898,8 @@ values are:
usage: PROG [-h] foo [foo ...]
PROG: error: too few arguments

.. _`argparse.REMAINDER`:

* ``argparse.REMAINDER``. All the remaining command-line arguments are gathered
into a list. This is commonly useful for command line utilities that dispatch
to other command line utilities::
Expand Down Expand Up @@ -1324,8 +1326,11 @@ The parse_args() method
created and how they are assigned. See the documentation for
:meth:`add_argument` for details.

By default, the argument strings are taken from :data:`sys.argv`, and a new empty
:class:`Namespace` object is created for the attributes.
* args_ - List of strings to parse. The default is taken from
:data:`sys.argv`.

* namespace_ - An object to take the attributes. The default is a new empty
:class:`Namespace` object.


Option value syntax
Expand Down Expand Up @@ -1467,6 +1472,7 @@ unambiguous (the prefix matches a unique option)::
An error is produced for arguments that could produce more than one options.
This feature can be disabled by setting :ref:`allow_abbrev` to ``False``.

.. _args:

Beyond ``sys.argv``
^^^^^^^^^^^^^^^^^^^
Expand All @@ -1488,6 +1494,7 @@ interactive prompt::
>>> parser.parse_args(['1', '2', '3', '4', '--sum'])
Namespace(accumulate=<built-in function sum>, integers=[1, 2, 3, 4])

.. _namespace:

The Namespace object
^^^^^^^^^^^^^^^^^^^^
Expand Down Expand Up @@ -2008,7 +2015,12 @@ A partial upgrade path from :mod:`optparse` to :mod:`argparse`:
* Replace ``(options, args) = parser.parse_args()`` with ``args =
parser.parse_args()`` and add additional :meth:`ArgumentParser.add_argument`
calls for the positional arguments. Keep in mind that what was previously
called ``options``, now in :mod:`argparse` context is called ``args``.
called ``options``, now in the :mod:`argparse` context is called ``args``.

* Replace :meth:`optparse.OptionParser.disable_interspersed_args`
by setting ``nargs`` of a positional argument to `argparse.REMAINDER`_, or
use :meth:`~ArgumentParser.parse_known_args` to collect unparsed argument
strings in a separate list.

* Replace callback actions and the ``callback_*`` keyword arguments with
``type`` or ``action`` arguments.
Expand Down