[Python-Dev] subclassing builtin data structures

[Alexander Belopolsky]

On Fri, Feb 13, 2015 at 1:19 PM, Alexander Belopolsky <
alexander.belopolsky at gmail.com> wrote:
>>
>> FWIW you're wrong when you claim that "a constructor is no different
from any other method". Someone else should probably explain this (it's an
old argument that's been thoroughly settled).
>
>
> Well, the best answer I've got in the past [1] was "ask on python-dev
since Guido called the operator overriding expectation." :-)


And let me repost this bit of history [1]:

Here is the annotated pre-r82065 code:

 39876 gvanrossum     def __add__(self, other):
 39876 gvanrossum         if isinstance(other, timedelta):
 39928 gvanrossum             return self.__class__(self.__days +
other.__days,
 39876 gvanrossum                                   self.__seconds +
other.__seconds,
 39876 gvanrossum                                   self.__microseconds +
other.__microseconds)
 40207    tim_one         return NotImplemented
 39876 gvanrossum


[1] http://bugs.python.org/issue2267#msg125979
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