inconsistency with += between different types ?

Andreas Leitgeb Andreas.Leitgeb at
Wed Aug 7 20:32:49 CEST 2002

Bernhard Herzog <bh at> wrote:
> list-python at (Christopher A. Craig) writes:
>> Andreas.Leitgeb at (Andreas Leitgeb) suggested:
>>> [ restrict __i...__-methods to enforce sane-ness ]
>> You do realize that at the end of this += would only apply to lists
>> [...] Because ints,
>> longs, floats, tuples, and in the future rationals are all immutable
>> and thus cannot return self.
> So what? Immutable objects don't have to implement __iadd__ et al. at
> all and in fact ints don't have __iadd__. Python falls back to calling
> __add__ and normal assignment automatically.

That's exactly what I meant.
For immutable objects, __iadd__ et al. simply make no sense (IMHO).

To Christopher and other defendants of status quo:
 Do you know of any real use that a not-self-mutating __ixxx__ 
 may have, which its non-i version __xxx__ could not do ?
 (I do *not* intend to argue that just because you perhaps cannot think 
  of any at the moment, that the suggestion would necessarily be good,   
  but if instead you happen to know a good use then we could instantly 
  short-cut the discussion.)

PS: The ability to write intendedly obfuscated Python does not count :-)
Newsflash: Sproingy made it to the ground !
  read more ... <>

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