Mercurial > public > mercurial-scm > hg
diff mercurial/thirdparty/attr/converters.py @ 34397:765eb17a7eb8
thirdparty: vendor attrs
The attrs package allows defining namedtuple-like classes with no weird
behavior and no runtime performance cost.
This patch vendors in attrs 17.2.0.
# no-check-commit
Differential Revision: https://phab.mercurial-scm.org/D867
| author | Siddharth Agarwal <sid0@fb.com> |
|---|---|
| date | Sun, 01 Oct 2017 04:14:16 -0700 |
| parents | |
| children | e1c586b9a43c |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mercurial/thirdparty/attr/converters.py Sun Oct 01 04:14:16 2017 -0700 @@ -0,0 +1,24 @@ +""" +Commonly useful converters. +""" + +from __future__ import absolute_import, division, print_function + + +def optional(converter): + """ + A converter that allows an attribute to be optional. An optional attribute + is one which can be set to ``None``. + + :param callable converter: the converter that is used for non-``None`` + values. + + .. versionadded:: 17.1.0 + """ + + def optional_converter(val): + if val is None: + return None + return converter(val) + + return optional_converter