Jim Jewett <[EMAIL PROTECTED]> wrote:
> (In http://mail.python.org/pipermail/python-dev/2005-October/057409.html,)
> Nick Coghlan suggested allowing attribute references as binding targets.
>
> > x = property("Property x (must be less than 5)")
>
> > def x.get(instance): ...
>
> Josiah shivered and said it was hard to tell what was even intended, and
> (in http://mail.python.org/pipermail/python-dev/2005-October/057437.html)
> Nick agreed that it was worse than
>
> > x.get = f given:
> > def f(): ...
>
> Could someone explain to me why it is worse?
def x.get(...): ...
Seems to imply that one is defining a method on x. This is not the case.
It is also confused by the x.get(instance) terminology that I doubt has
ever seen light of day in production code. Instance of what? Instance
of x? The class? ...
I'm personally averse to the 'given:' syntax, if only because under
certain situations, it can be reasonably emulated.
> I understand not wanting to modify object x outside of its definition.
>
> I understand that there is some trickiness about instancemethods
> and bound variables.
>
> But these objections seem equally strong for both forms, as well
> as for the current "equivalent" of
>
> def f(): ...
> x.get = f
>
> The first form (def x.get) at least avoids repeating (or even creating)
> the temporary function name.
>
> The justification for decorators was to solve this very problem within
> a module or class. How is this different? Is it just that attributes
> shouldn't be functions, and this might encourage the practice?
Many will agree that there is a problem with how properties are defined.
There are many proposed solutions, some of which use decorators, custom
subclasses, metaclasses, etc.
I have a problem with it because from the description, you could use...
def x.y.z.a.b.c.foobarbaz(...):
...
...and it woud be unclear to the reader or writer what the hell
x.y.z.a.b.c is (class, instance, module), which can come up if the
definition/import of x is far enough away from the definition of
x.<blah> . Again, ick.
- Josiah
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