[Python-Dev] Scoping vs augmented assignment vs sets (Re: 'fast locals' in Python 2.5)

[Terry Reedy]

"Boris Borcic" <bborcic at gmail.com> wrote in message 
news:e6on1i$bvc$1 at sea.gmane.org...
Terry Reedy wrote:
>> Your transformation amounted to switching from collection mutation to
>> object rebinding.  In Python, that is a crucial difference.

>Ok, that is a crucial difference. The question becomes : is that 
>difference in
>the case of augmented assignment maintained for practical or for purity 
>aka
>ideological reasons ?

Consistency.  a op=b is almost the same as a = a op b except 1) 'a' is 
computed only once and 2) if a is mutable, type(a) may choose to do op in 
place via the call to __iop__ instead of __op__.  But in any case, the 
assigment is made and 'a', if a name, is bound to the result.

Anyway, this will not change for 2.x and further discussion is really 
c.l.p. material.

Terry Jan Reedy