[Python-ideas] Augmented assignment syntax for objects.

[Brice PARENT]

Le 26/04/17 à 19:46, Mike Miller a écrit :
>
> On 2017-04-26 04:12, Brice PARENT wrote:
>> Why not simply do this :
>>
>> class MyClass:
>>     def _set_multiple(self, **kwargs):
>>         for key, value in kwargs.items():
>>             setattr(self, key, value)
>>
>>     def __init__(self, a, b, c):
>>         self._set_multiple(a=a, b=b, c=c)
>
> If the goal is to not have to type out argument names three times (in 
> DRY fashion), this doesn't quite fit the bill.
>
> -Mike
>
You still save some typing (no need for /self./ for every assignment), 
and a lot of vertical space.

Also, it allows you to use any dict (like **kwargs) as well as doing 
very common things like :

class MyClass:
     def _set_multiple(self, **kwargs):
         for key, value in kwargs.items():
             setattr(self, key, value)

     def __init__(self, a, b, c):
         self._set_multiple(a=a, _b=b)

which is equivalent to the following really common pattern :

class MyClass:
     def __init__(self, a, b, c):
         self.a = a
         self._b = b

(well, I didn't try it, but it should work)
This means your public API (the signature of the constructor here) has 
no incidence on the way the class works on the inside. Meaning an 
attribute can become a property, which is something that occurs from 
time to time, and you just need to update your constructor 
(self._set_multiple(a=a, b=b) becomes self._set_multiple(a=a, _b=b)) and 
you're done.
And if at some point your community doesn't think "a" is a good name for 
your variable, you can update it to something every user will understand 
without any significant change to your class 
(self._set_multiple(a=way_better, _b=b)).

-Brice

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