[Python-Dev] statically nested scopes

Guido van Rossum guido@python.org
Fri, 03 Nov 2000 08:12:11 -0500

> That's just what I was trying to say all along: statically
> nested scopes don't buy you anything except maybe for lambdas
> and nested functions

That's a tautology -- that's what nested scopes are FOR!

> (which is bad style programming, IMHO too).

Not always.  The keyword argument hack is so common that it must serve
a purpose, and that's what we're trying to fix -- for lambda's *and*
nested functions (which are semantically equivalent anyway).

> The only true argument for changing scoping I see is that
> of gained purity in language design... without much practical
> use.

But there is practical use: get rid of the unintuitive, unobvious and
fragile keyword argument hack.

> Other issues that need sorting out:
> x = 2
> class C:
>   x = 1
>   C = 'some string'
>   def a(self):
>      print x
>   def b(self):
>      global x
>      x = 3
> class D(C):
>   C = 'some string'
>   def a(self):
>      C.a(self)
>      print C
> o = C()
> o.a()
> o.b()
> o.a()
> o = D()
> o.a()
> What would the output look like under your proposal ?

This is a good point!  If we considered the class as a nested scope
here, I think it might break too much code, plus it would allow a new
coding style where you could reference class variables without a self
or <classname> prefix.  I don't like that prospect, so I'm in favor
for ruling this out.

--Guido van Rossum (home page: http://www.python.org/~guido/)