Nested scopes: why is it weird?

[Alex Martelli]

Scott Long wrote:
        ...
> In this spirit, why not place variables into scopes dynamically as well?

Because it doesn't work well.  The original LISP had dynamic scoping, and 
it was *by far* the biggest weakness of that otherwise-great language.  
Ever since Scheme introduced lexical scoping, Lisp rushed to copy it on 
that point, and Common Lisp now scopes lexically -- and works much better 
because of that.

> The problem doesn't occur if you associate scopes with suites instead of
> function defs (equivalent to block scopes in C/C++ for example). A suite
> (or block) has a definite "first statement". 

Yes, but that granularity would be utterly and totally useless for 
determining local variables.  If a variable was local to each block that 
bound it, you could never modify any variable in a statement guarded by an 
if without first artificially accessing the variable to show it's the 
"outer" one you mean -- what a nightmare!

Fine-grained scoping can only work hand in hand with declarations, and 
Python (thanks be) does not have them.


Alex