Darren Dale, 08.11.2010 15:34: > Python-2.6 extended the definition of property to include getter, > setter, and deleter methods that can be used as decorators. This > allows a really nice pattern for declaring properties without > populating the namespace with a bunch of private methods: > > class Foo(object): > > _bar = None > @property > def bar(self): > return self._bar > @bar.setter > def bar(self, val): > self._bar = val > > What happens is @bar.setter makes a copy of bar, updates the copy to > use the decorated method as the setter, and returns the copy, which is > then bound to the name of the decorated function. The decorated > function has to be called bar, so that the updated copy is bound to > bar, replacing the original. > > Attempting to cythonize this example yields an error: > > $ python setup.py build_ext --inplace > running build_ext > cythoning test_property.pyx to test_property.c > > Error converting Pyrex file to C: > ------------------------------------------------------------ > ... > _bar = None > @property > def bar(self): > return self._bar > @bar.setter > def bar(self, val): > ^ > ------------------------------------------------------------ > > /Users/darren/temp/test/test_property.pyx:11:4: 'bar' already declared > > Would it be possible for Cython to support this pattern?
The problem is not the property behaviour, it's the mapping from a Python function/method to a C function, which must have a unique name. Currently, functions are unique within one namespace, be it the module namespace or a class body namespace. They are actually looked up statically, not dynamically in definition order, so the fix is not as easy as adding a counted ID to the C-level name. The above might actually work if you change one of the method names, i.e. either the getter or setter name. If it works as you say, the setter name shouldn't have any impact on the result. Stefan _______________________________________________ Cython-dev mailing list [email protected] http://codespeak.net/mailman/listinfo/cython-dev
