Re: variable semantics vs value semantics (was Re: Interfacing lua with C)

[RLake@...]

Lucas Ackerman escribió:

> Nonetheless I'm happy to break out some CS-fu and contribute.  As Peter
> pointed out, Lua's untyped nature makes defining type-dependant
> operations on variables inconvenient, if not outright impossible.  It
> might help (as usual) if you could give some context for what sort of
> system you're building and what role Lua is to play in it.  One way or
> another though, you want to access C objects (functions and state)
> through Lua. In C, variables are typed as well as objects.  This means
> that assignment to a variable refers to altering the value in memory
> referenced by that name, storing a different value (essentially copying
> it there, or doing whatever the object type's assignment operator
> specifies).

Permit me to disagree. "In C, variables are typed as well as objects" is
not true. In C, variables are typed (at compile time) and objects are just
bits. In C++ objects have a bit of type, but not all of it, and you can
still treat them as though they were just bits.

This is, of course, an endless debate: functional language advocates
(Schemes, Lispers, Haskellites, etc.) would say that their languages are
"strongly-typed" because values never lose their type. Cers and Fortranians
beg to differ. I think the terminology is probably not helpful.

In any event, in Lua, variables are just bindings; local variables are
names of values. If you want a mutable local object, use a local table and
assign to its keys. That will do exactly what you want and does not involve
any magic. Why would I want to turn the local namespace into a table? I can
already create as many local tables as I want. Then I know exactly when I'm
creating overhead and why.