[Python-ideas] collections.Counter should implement __mul__, __rmul__

[Serhiy Storchaka]

18.04.18 21:45, Tim Peters пише:
> (*) The obvious implementation:
> 
>      def __mul__(self, other):
>         if isinstance(other, Sized):
>             raise TypeError("cannot multiply Counter by Sized type %s"
> % type(other))

Wouldn't be better to return NotImplemented here?

>          result = Counter()
>          for k, v in self.items():
>              result[k] = v * other
>          return result

If discard non-positive values, this will automatically make multiplying 
Counter by Counter (or by sequence) invalid, because they are not 
comparable with 0.

          for k, v in self.items():
              v = v * other
              if v > 0:
                  result[k] = v * other