From: Brian Candler <B.Candler@...>
Date: 2003-02-02T19:24:32+09:00
Subject: Re: Local variables & blocks

On Sun, Feb 02, 2003 at 09:30:12AM +0100, ts wrote:
> B> Unfortunately, although I receive ruby-talk in digest form, there are some
> B> weeks when I simply have to delete every day's mails. That's just how it
> B> goes. I did read [52440], [63087] and [63100] though, and the terminology
> B> was ambiguous to me. Does "shadowed" mean "aliased" or "hidden"?
> 
>  It's simple :
> 
>     * all variables are local except variables found between || which are
>       block local
> 
>     * you have a warning (and shadowing) if a variable found between || was
>       previously declared

Thanks, I just wasn't sure of the definition of "shadowing". As far as I can
see it means "a completely different variable, which just happens to have
the same name as another one in an outer scope"

In C it would be:

#include <stdio.h>
int main(void)
{
 int x = 1;
 {
   int x = 2;         /* this x 'shadows' the other one? */
   printf("%d\n",x);  /* it's just a different variable */
 }
 printf("%d\n",x);
 return 0;
}

Incidentally, gcc -Wall doesn't give any warnings with that program, since
it's a perfectly reasonable thing to do. The only reason Ruby would warn is
because it's not backwards-compatible. I would imagine that eventually this
warning would be turned off.

Regards,

Brian.