# Tai Sakuma <tai.sakuma@gmail.com>
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[docs]class LambdaStr:
"""select events to which a lambda returns True.
A lambda should be given as a string to ``__init__`` and will be
evaluated in ``begin()``. This is because a lambda is not
picklable.
In the multiprocessing mode, ``__init__()`` is called in the main
process. Then, the instance will be pickled and sent to
subprocesses. ``begin()`` will be called in the subprocesses.
"""
[docs] def __init__(self, lambda_str, name=None):
self.name = name if name is not None else lambda_str
self.lambda_str = lambda_str
def __repr__(self):
return '{}(name={!r}, lambda_str={!r})'.format(
self.__class__.__name__,
self.name,
self.lambda_str
)
def begin(self, event):
self.func = eval('lambda ' + self.lambda_str)
def event(self, event):
try:
return self.func(event)
except BaseException as e:
raise ValueError('{}: error in executing "{}". raised -- {}: {}'.format(
self.__class__.__name__,
self.lambda_str, type(e).__name__, e
))
def __call__(self, event):
return self.event(event)
def end(self):
self.func = None
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