property decorator?

[Chris Angelico]

On Thu, Dec 21, 2017 at 2:38 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Wed, Dec 20, 2017 at 5:56 PM, Irv Kalb <Irv at furrypants.com> wrote:
>> 2)  Alternatively, if the getter was going to use the @property decorator, then it would seem complimentary  to have the decorator name for the associated setter function to have the word "property" in its also, something like @propertySetter.
>
> Perhaps this could have been done, but unlike the getter, the setter
> is being defined on a property that now already exists. In this case
> <name> has to be referenced somewhere within the decorator or else the
> setter property will simply replace the getter property, rather than
> augment and then replace it.
>
> I suppose what it boils down to is that there's no particular reason
> to look up "property" again since the getter already declared that
> this is a property.

It's more than that. It's actually not easy to locate something by its
name while you're in process of setting it up. Consider:

class Demo:
    @getter
    def foo(self):
        ...
    @setter
    def foo(self, value):
        ...

Only one thing can be bound to Demo.foo, which means that that one
thing has to be a property capable of calling on the getter and the
setter. That means that when setter(foo) is called, it would need to
locate the pre-existing "foo" property and augment it. That's actually
pretty hard to do reliably (remember that there are many contexts in
which this can be called).

ChrisA