def test_notNone(self):
"""
If the first parameter to a `maybe`-wrapped function is not ``None``
then the result of the wrapped function is returned.
"""
self.assertThat(
maybe(identity)(42),
Equals(42))
self.assertThat(
maybe(identityv)(42, 1, a=2),
Equals(((42, 1), {'a': 2})))
def test_customDefault(self):
"""
A custom value can be passed for the ``default`` parameter.
"""
default = object()
self.assertThat(
maybe(identity, default=default)(None),
Is(default))
self.assertThat(
maybe(identityv, default=default)(None, 1, a=2),
Is(default))
def test_none(self):
"""
If the first parameter to a `maybe`-wrapped function is ``None`` then
the result of that function is immediately ``None``.
"""
self.assertThat(
maybe(identity)(None),
Is(None))
self.assertThat(
maybe(identityv)(None, 1, a=2),
Is(None))
def many(func):
"""
Create a callable that applies ``func`` to every value in a sequence.
If the value is not a sequence then an empty list is returned.
:type func: `callable`
:param func: Callable to be applied to the first result.
"""
def _many(result):
if _isSequenceTypeNotText(result):
return map(func, result)
return []
return maybe(_many, default=[])
def one(func, n=0):
"""
Create a callable that applies ``func`` to a value in a sequence.
If the value is not a sequence or is an empty sequence then ``None`` is
returned.
:type func: `callable`
:param func: Callable to be applied to each result.
:type n: `int`
:param n: Index of the value to apply ``func`` to.
"""
def _one(result):
if _isSequenceTypeNotText(result) and len(result) > n:
return func(result[n])
return None
return maybe(_one)
