Re: Lua Library Design Workshop

[Roberto Ierusalimschy <rieru@...>]

On Sun, 24 Feb 2002, John Belmonte wrote:

> We've come to it in a roundabout fashion, but it seems to me that the syntax
>
>      global (T) *
>
> would be better recognized as:
>
>      namespace T

Namespaces is only one of the uses of the global declaration. But remember
that, in Lua, almost every function is global (print, write, etc.), so
a simple "namespace T" would not be very helpful. Moreover, a simple
"namespace T" helps to define modules, but not to use them.


> However I'm not sure I understood the intended semantics of your proposal,

The semantics is: "global (exp) name-list" translates to

  _temp = exp

after that, any use of a name in name-list is read as "_temp.name",
subjected to the usual visibility rules for variable declarations.
If name-list is '*', then the rule applies to any name not declared
in another local/global declaration. So,

> 1) the access rules apply not only when the module is
> executed, but also when functions defined within the module are
> executed,

Yes, if the functions are declared inside the scope of the global
declaration. (The change from "name" to "_temp.name" is done at compile
time...)


> 2) in nesting of dofile's/modules, the access rules properly nest.

Scopes in "dofile"s do not nest.


> If upvalues were any lesson, we'll end up with proper namespaces despite
> any contrary intentions ;-).

What do you call "proper namespace"?

-- Roberto