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import collections.abc |
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import functools |
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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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@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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