Re: [ANN] Lua 5.2.0 (beta-rc2) now available

[Gé Weijers <ge@...>]

On Wed, 22 Jun 2011, Roberto Ierusalimschy wrote:

>  -- example 2
>  do
>    ::label::   -- 1
>    goto label
>  end
>  ::label::   -- 2
>
> So, your second option should also disallow example 2. The first
> label is not visible when the second is declared, but the second
> label is visible when the first one is declared!  (Nevertheless,
> this seems a nice compromise between one-per-function and one-per-
> block.)

I realize that.

The visibility of labels should probably follow the scope rules you'd find 
in languages like Algol 68, with extra restrictions. The rules there make 
this a correct program:

BEGIN
        PROC foo = (INT i)VOID: (var := i);
        INT var := 0;
        foo(4);
        print((var,newline))
END

The assignment to 'var' inside procedure 'foo' textually precedes the 
declaration of 'var', which is legal. I'm not suggesting to do this for
variables in Lua, BTW, or

local print = print

would not be a valid idiom.


Ge'