[Python-ideas] Decorators for variables

[Ian Kelly]

(Resending to correct list. Sorry about that.)

On Fri, Apr 1, 2016 at 11:25 AM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> On Fri, Apr 1, 2016 at 11:14 AM, Matthias welp <boekewurm at gmail.com> wrote:
>>> An example of the transformation would help here
>>
>> An example, that detects cycles in a graph, and doesn't do an update if
>> the graph has cycles.
>
> Thanks.
>
>> class A(object):
>>     def __init__(self, parent):
>>         @prevent_cycles
>>         self.parent = parent
>
> I think you'll find that this doesn't work. Properties are members of
> the class, not of instances of the class.
>
>> This would prevent cycles from being created in this object A, and would
>> make
>> some highly reusable code. The same can be done for @not_none, etc, to
>> prevent
>> some states which may be unwanted.
>
> But you could accomplish the same thing with "self.parent =
> prevent_cycles(parent)". So I'm still not seeing how the use of the
> decorator syntax eliminates repetition.