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_method_cache = {}
class methodcaller(object):
"""
Return a callable object that calls the given method on its operand.
Unlike the builtin `operator.methodcaller`, instances of this class are
serializable
"""
__slots__ = ('method',)
func = property(lambda self: self.method) # For `funcname` to work
def __new__(cls, method):
if method in _method_cache:
return _method_cache[method]
self = object.__new__(cls)
self.method = method
_method_cache[method] = self
return self
def __call__(self, obj, *args, **kwargs):
return getattr(obj, self.method)(*args, **kwargs)
def __reduce__(self):
return (methodcaller, (self.method,))
def __str__(self):
return "<%s: %s>" % (self.__class__.__name__, self.method)
__repr__ = __str__
class MethodCache(object):
"""Attribute access on this object returns a methodcaller for that
attribute.
Examples
--------
>>> a = [1, 3, 3]
>>> M.count(a, 3) == a.count(3)
True
"""
__getattr__ = staticmethod(methodcaller)
__dir__ = lambda self: list(_method_cache)
M = MethodCache()
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