[Python-ideas] Json object-level serializer

[Tarek Ziadé]

On Thu, Jul 29, 2010 at 3:49 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Le jeudi 29 juillet 2010 à 15:42 +0200, Tarek Ziadé a écrit :
>> On Thu, Jul 29, 2010 at 3:34 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
>> > On Thu, 29 Jul 2010 15:25:20 +0200
>> > Tarek Ziadé <ziade.tarek at gmail.com> wrote:
>> >>
>> >> That makes sense. OTHO, if we drop the idea of having a __magical__ method,
>> >> we could have an collections' ABC instead, called JSONSerializable,
>> >> with one method to override,
>> >>
>> >> This is more about declaring the interface rather than adding yet
>> >> another __magic__ method
>> >>
>> >> That's a nice OOP pattern to have imho
>> >
>> > Python is supposed to be duck-typed. It would be strange to add a
>> > couple of random exceptions to that general rule. Moreover, having to
>> > *both* derive an existing class and implement the single method defined
>> > on that class is one complication too many.
>>
>> Not sure to follow here, since ABCs are about having an object
>> supporting a series of methods no matter what are the parent classes.
>> e.g. this is closer to the concept of "interfaces".
>>
>> IOW you don't need to derive from a parent class, you just to need to provide
>> a given set of methods, and ABC provides a ways to check that an
>> object has that signature.
>
> Ok, but then how does it avoid having a __magic__ method? You can't use
> a normal name such as "to_json" because then an existing class with that
> method could be wrongly inferred as implementing your new ABC, and break
> existing code.

yes that's a possible side-effect, unless we explicitely register those class
Using ABC's register technique.

>
> Besides, defining an ABC for a single, module-specific method sounds
> rather overkill. This reminds of me of projects plagued by an overuse of
> interfaces for every possible concept.

Thats what Iterator did in ABC though.