Re: Down with Upvalues

[Edgar Toernig <froese@...>]

ping "John D. Ramsdell" wrote:
> 
> Some of the postings on lua-user.org demonstrate that upvalues are
> very confusing.  They confuse some people so much that they think the
> current version of Lua is lexically scoped!  Let's get some basics
> straight.
> 
> Lua is a statically scoped language in which each variable has either
> local or global scope.

Yeah.  Let's get it straight :-)

I think the confusion is on your side because you make a distinction
between lexical and static scoping.  It's the same.  If you think
I'm wrong give a reference to a text that defines the difference.
By your understanding C (or GCC if you require function nesting) is
not lexically scoped either and a lot of people will disagree.

> Functions can be defined within functions,
> however, a nested function does not have access to variables defined
> in any of its enclosing functions.  Therefore, Lua is not lexically
> scoped.

You are focused very much on function nesting.  There are more kind of
nesting constructs in Lua (for-do-end, while-end, do-end, ...).  Just
because some scope accesses are forbidden/unsupported does not mean
that it's not lexically scoped.  What if i.e. Pascal had a "private"
keyword for locals which prohibits access from other functions.  Would
this make Pascal no longer lexically scoped?

Ciao, ET.