[Python-Dev] Declaring setters with getters

[Guido van Rossum]

On Nov 10, 2007 11:09 AM, Steven Bethard <steven.bethard at gmail.com> wrote:
> On Nov 10, 2007 11:31 AM, Guido van Rossum <guido at python.org> wrote:
> > Unless I get negative feedback really soon I plan to submit this later
> > today. I've tweaked the patch slightly to be smarter about replacing
> > the setter and the deleter together if they are the same object.
>
> Definitely +1 on the basic patch.
>
> Could you explain briefly the advantage of the "hack" that merges the
> set and del methods?  Looking at the patch, I get a little nervous
> about this::
>
>         @foo.setter
>         def foo(self, value=None):
>             if value is None:
>                 del self._foo
>             else:
>                 self._foo = abs(value)
>
> That means that ``c.foo = None`` is equivalent to ``del c.foo`` right?

Which is sometimes convenient. But thinking about this some more I
think that if I *wanted* to use the same method as setter and deleter,
I could just write

@foo.setter
@foo.deleter
def foo(self, value=None): ...

So I'm withdrawing the hacks, making the code and semantics much simpler.

See propset3.diff in http://bugs.python.org/issue1416 .

-- 
--Guido van Rossum (home page: http://www.python.org/~guido/)