Source code for pyramid.decorator

[docs] class reify: """Use as a class method decorator. It operates almost exactly like the Python ``@property`` decorator, but it puts the result of the method it decorates into the instance dict after the first call, effectively replacing the function it decorates with an instance variable. It is, in Python parlance, a non-data descriptor. The following is an example and its usage: .. doctest:: >>> from pyramid.decorator import reify >>> class Foo: ... @reify ... def jammy(self): ... print('jammy called') ... return 1 >>> f = Foo() >>> v = f.jammy jammy called >>> print(v) 1 >>> f.jammy 1 >>> # jammy func not called the second time; it replaced itself with 1 >>> # Note: reassignment is possible >>> f.jammy = 2 >>> f.jammy 2 """ def __init__(self, wrapped): self.wrapped = wrapped self.__name__ = wrapped.__name__ self.__doc__ = wrapped.__doc__ def __get__(self, inst, objtype=None): if inst is None: return self val = self.wrapped(inst) # reify is a non-data-descriptor which is leveraging the fact # that it is not invoked if the equivalent attribute is defined in the # object's dict, so the setattr here effectively hides this descriptor # from subsequent lookups setattr(inst, self.wrapped.__name__, val) return val