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class LazyProperty(object):
"""
Decorator for easier creation of ``property`` from potentially expensive to
calculate attribute of the class.
Usage::
class Foo(object):
@LazyProperty
def bar(self):
print 'Calculating self._bar'
return 42
Taken from http://blog.pythonisito.com/2008/08/lazy-descriptors.html and
used widely.
"""
def __init__(self, func):
self._func = func
self.__module__ = func.__module__
self.__name__ = func.__name__
self.__doc__ = func.__doc__
def __get__(self, obj, klass=None):
if obj is None:
return self
result = obj.__dict__[self.__name__] = self._func(obj)
return result
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