templates: add filter to reverse list
The filter supports only lists because for lists, it’s straightforward to
implement. Reversing text doesn’t seem very useful and is hard to implement.
Reversing the bytes would break multi-bytes encodings. Reversing the code
points would break characters consisting of multiple code points. Reversing
graphemes is non-trivial without using a library not included in the standard
library.
"""
Commonly useful filters for :func:`attr.asdict`.
"""
from __future__ import absolute_import, division, print_function
from ._compat import isclass
from ._make import Attribute
def _split_what(what):
"""
Returns a tuple of `frozenset`s of classes and attributes.
"""
return (
frozenset(cls for cls in what if isclass(cls)),
frozenset(cls for cls in what if isinstance(cls, Attribute)),
)
def include(*what):
r"""
Whitelist *what*.
:param what: What to whitelist.
:type what: :class:`list` of :class:`type` or :class:`attr.Attribute`\ s
:rtype: :class:`callable`
"""
cls, attrs = _split_what(what)
def include_(attribute, value):
return value.__class__ in cls or attribute in attrs
return include_
def exclude(*what):
r"""
Blacklist *what*.
:param what: What to blacklist.
:type what: :class:`list` of classes or :class:`attr.Attribute`\ s.
:rtype: :class:`callable`
"""
cls, attrs = _split_what(what)
def exclude_(attribute, value):
return value.__class__ not in cls and attribute not in attrs
return exclude_