Tricky Areas in Python
fredrik at pythonware.com
Mon Oct 24 12:36:18 CEST 2005
Steven D'Aprano wrote:
> Those two are easy. However, and this is where I show
> my hard-won ignorance, and admit that I don't see the
> problem with the property examples:
>> class Base(object)
>> def getFoo(self): ...
>> def setFoo(self): ...
>> foo = property(getFoo, setFoo)
>> class Derived(Base):
>> def getFoo(self): ....
the property call in Base binds to the Base.getFoo and Base.setFoo method
*objects*, not the names, so overriding getFoo in Derived won't affect the foo
to get proper dispatching for accessors, you need to add an extra layer:
def getFoo(self): ...
def setFoo(self, ...): ...
def getFooDispatcher(self): self.getFoo() # use normal lookup
def setFooDispatcher(self, ...): self.setFoo(...) # use normal lookup
foo = property(getFooDispatcher, setFooDispatcher)
this gotcha is the motivation for this proposal:
(see that thread for more on this topic)
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