sapling/mercurial/thirdparty/attr/converters.py
Jun Wu 2946a1c198 codemod: use single blank line
Summary: This makes test-check-code cleaner.

Reviewed By: ryanmce

Differential Revision: D6937934

fbshipit-source-id: 8f92bc32f75b9792ac67db77bb3a8756b37fa941
2018-04-13 21:51:08 -07:00

24 lines
530 B
Python

"""
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