__iadd__ and fellows missing (Python 2.2)

[Ralf Juengling]

Michael Hudson <mwh at python.net> writes:

> Ralf Juengling <juenglin at informatik.uni-freiburg.de> writes:
> 
> > Shouldn't I find the special methods '__iadd__' et al, when
> > asking for the attributes of 'int'?
> 
> ints are immutable, so they don't implement __iadd__.  lists do:
> 

Hm. But then an expression 'i+=1' should cause an error if 'i'
is an int...

>>> i = 1
>>> type(i) 
<type 'int'>
>>> id(i)
134526912
>>> i+=1
>>> id(i)
134526852
>>> 

I understand now, that 'i+=1' is no real in-place operation but
just a shortcut for 'i=i+1' since int is immutable. The language
reference states that this is okay, anyhow, I find it confusing.

For the sake of clarity, an 'in-place' operation should really 
work in-place, don't you think?


Cheers,
Ralf



> > I couldn't find them either in ther operator-module:
> 
> Hmm, I think the issue here is that 
> 
> x += y
> 
> translates (in the presence of an __iadd__ method) roughly to 
> 
> x = x.__iadd__(x, y)
> 
> and you can't do that in the form of 
> 
> operator.blah(x,y)
> 
> .  Or it might just be oversight.
> 
> Cheers,
> M.
> 
> -- 
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