[Python-ideas] Where-statement (Proposal for function expressions)

[Greg Ewing]

Daniel Stutzbach wrote:

> If the
> left-hand side were in the where-block's scope, then:
> 
> x = 0
> x = i where:
>    i = 5
> print x
> 
> Would print "0" not "5".

My intuitive expectations are different for assignment
to a bare name vs. assignment to an item or attribute.
In

   x = i where:
     i = 5

I would expect x to be bound in the current scope,
not the where-block scope. But I would expect

   x[i] = 5 where:
     x = y
     i = 7

to be equivalent to

   y[7] = 5

i.e. both x and i are *evaluated* in the where-block
scope.

I'm not sure where this leaves us with respect to
augmented assignment, though. If you follow it to
its logical conclusion, then

   x += i where:
     i = 5

should be equivalent to

   x = x.__iadd__(i) where:
     i = 5

and then the evaluation and rebinding of 'x' would
happen in different scopes!

-- 
Greg