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