Why not a, b += i, j? (augmented assignment via tuple unpacking)

[Jeff Epler]

On Wed, Nov 27, 2002 at 05:49:59PM +1300, Greg Ewing wrote:
> Jeff Epler wrote:
> 
> >but in that case, what is
> >    a, b += t
> >equivalent to?
> 
> 
> Obviously it's
> 
>    a, b = iadd(a, t[0]), iadd(a, t[1])
> 
> >What about
> >    t += a, b
> 
> 
> This is already meaningful:
> 
>    t = iadd(t, (a, b))

Right now
    t = i, j
    a, b = t
    del t
is equivalent to
    a, b = i, j
except that the temporary t is never created (it resides on the stack)

But that means that you'd want
    t = a, b
    t += i, j
    a, b = t
    del t
to be equivalent to
    a, b += i, j
but now 't += (i, j)' has been given two different meanings -- the one
it has already, and the one it would need to have to make "augmented
assignment via tuple unpacking" work in the "desired" way.

Jeff