[Python-Dev] Explicit Lexical Scoping (pre-PEP?)

[Terry Reedy]

"Boris Borcic" <bborcic at gmail.com> wrote in message 
news:e90j6o$fij$1 at sea.gmane.org...
> I agree with you (and argued it in "scopes vs augmented assignment vs 
> sets"
> recently) that mutating would be sufficient /if/ the compiler would view
> augmented assignment as mutations operators :

Mutation is an operation on objects.  Binding is an operation on 
namespaces.  The difference between objects and namespaces (and the actions 
thereupon) is fundamental to Python.  Asking the interpreter to view one 
thing as something else which it isn't can only lead to more confusion.  In 
particular, asking that arithmetic operations on immutable numbers be seen 
as mutations seems wacky to me.

> which it doesn't as far as  concerns scopes where a variable
> appears as target only of /augmented/ assignments.

The interpreter/compiler, as far as I can think, never views binding as 
mutation, nor should it.  The request that it do so makes me wonder whether 
it might have been a mistake to allow mutable objects in an augmented 
assignment to choose to implement the associated operation as an in-place 
mutation.

Terry Jan Reedy