pyramid.decorator のソースコード
[ドキュメント]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.__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