74 lines
1.7 KiB
Python
74 lines
1.7 KiB
Python
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import collections.abc
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import functools
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# from jaraco.functools 3.5
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def pass_none(func):
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"""
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Wrap func so it's not called if its first param is None
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>>> print_text = pass_none(print)
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>>> print_text('text')
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text
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>>> print_text(None)
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"""
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@functools.wraps(func)
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def wrapper(param, *args, **kwargs):
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if param is not None:
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return func(param, *args, **kwargs)
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return wrapper
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# from jaraco.functools 4.0
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@functools.singledispatch
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def _splat_inner(args, func):
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"""Splat args to func."""
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return func(*args)
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@_splat_inner.register
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def _(args: collections.abc.Mapping, func):
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"""Splat kargs to func as kwargs."""
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return func(**args)
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def splat(func):
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"""
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Wrap func to expect its parameters to be passed positionally in a tuple.
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Has a similar effect to that of ``itertools.starmap`` over
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simple ``map``.
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>>> import itertools, operator
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>>> pairs = [(-1, 1), (0, 2)]
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>>> _ = tuple(itertools.starmap(print, pairs))
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-1 1
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0 2
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>>> _ = tuple(map(splat(print), pairs))
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-1 1
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0 2
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The approach generalizes to other iterators that don't have a "star"
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equivalent, such as a "starfilter".
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>>> list(filter(splat(operator.add), pairs))
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[(0, 2)]
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Splat also accepts a mapping argument.
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>>> def is_nice(msg, code):
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... return "smile" in msg or code == 0
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>>> msgs = [
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... dict(msg='smile!', code=20),
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... dict(msg='error :(', code=1),
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... dict(msg='unknown', code=0),
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... ]
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>>> for msg in filter(splat(is_nice), msgs):
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... print(msg)
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{'msg': 'smile!', 'code': 20}
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{'msg': 'unknown', 'code': 0}
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"""
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return functools.wraps(func)(functools.partial(_splat_inner, func=func))
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