[Python-Dev] __str__ vs. __unicode__

[Walter Dörwald]

M.-A. Lemburg wrote:
> Walter Dörwald wrote:
> 
>> M.-A. Lemburg wrote:
>>
>>  > [...]
>>
>>> __str__ and __unicode__ as well as the other hooks were
>>> specifically added for the type constructors to use.
>>> However, these were added at a time where sub-classing
>>> of types was not possible, so it's time now to reconsider
>>> whether this functionality should be extended to sub-classes
>>> as well.
>>
>> So can we reach consensus on this, or do we need a
>> BDFL pronouncement?
> 
> I don't have a clear picture of what the consensus currently
> looks like :-)
> 
> If we're going for for a solution that implements the hook
> awareness for all __<typename>__ hooks, I'd be +1 on that.
> If we only touch the __unicode__ case, we'd only be created
> yet another special case. I'd vote -0 on that.
 > [...]

Here's the patch that implements this for int/long/float/unicode:
http://www.python.org/sf/1109424

Note that complex already did the right thing.

For int/long/float this is implemented in the following way:
Converting an instance of a subclass to the base class is done
in the appropriate slot of the type (i.e. intobject.c::int_int()
etc.) instead of in PyNumber_Int()/PyNumber_Long()/PyNumber_Float().
It's still possible for a conversion method to return an instance
of a subclass of int/long/float.

Bye,
    Walter Dörwald