Dynamic property names on class

[Bryan]

On Nov 13, 9:34 am, "Diez B. Roggisch" <de... at nospam.web.de> wrote:
> Bryan schrieb:
>
>
>
> > I have several properties on a class that have very similar behavior.
> > If one of the properties is set, all the other properties need to be
> > set to None.  So I wanted to create these properties in a loop like:
>
> > class Test(object):
> >    for prop in ['foo', 'bar', 'spam']:
> >            # Attribute that data is actually stored in
> >            field = '_' + prop
> >            # Create getter/setter
> >            def _get(self):
> >                    return getattr(self, field)
> >            def _set(self, val):
> >                    setattr(self, field, val)
> >                    for otherProp in prop:
> >                            if otherProp != prop: setattr(self, '_' + otherProp, None)
> >            # Assign property to class
> >            setattr(Test, prop, property(_get, _set))
>
> > t = Test()
> > t.foo = 1
> > assert t.bar == t.spam == None
>
> > But the class Test is not defined yet, so I can't set a property on
> > it.  How can I do this?
>
> With a metaclass, or a post-class-creation function. Which is a
> metaclass without being fancy.
>
> Just put your above code into a function with the class in question as
> argument, and invoke it after Test is defined.
>
> Diez

I think there are some closure issues with this as I am getting very
strange results.  I think all properties have the getter/setters of
whatever the last item in the list was.
t.foo = 'settingFoo' actually sets t.spam, as 'spam' was the last
property generated.