🚀 go-pugleaf

In article <6495326.71820.1619@kcbbs.gen.nz> martin@kcbbs.gen.nz
(Martin Kealey) writes:

[snip]

> It is a new contruct, and therefore doesn't yet have a "natural spot".
> Putting the "label" of the loop *before* it doesn't strike me as a
> particularly natural place since the result of a break is to jump *after*
> the loop.  I would argue that putting the name next to the loop exit
> condition is the most natural place for it, but that's just my opinion.
> 
> Perl & Java don't have to cope with the ambiguity of a goto label, so they
> are free to re-use the "label :" format.
> 
> PLEASE EVERYONE READ THIS:
> 
> The point of creating a new grammatical form for loop names is to ENSURE
> (1) that they CAN'T become the target of a goto, and
> (2) a later maintainer can see that simply by looking at the loop control -
>     without having to go searching for a break or continue to know that
>     it is a loop name rather than a goto label.
> 
> Since we would be modifying the grammar for one part of the language (break
> and continue) there is little point in arguing against modifications
> elsewhere, since they'll both be introduced simultaneously.

I can't agree more...

> My opinion is that this should be further strengthened - a loop should be
> able to have multiple names, but each name must be used exactly once,

So far so good...

> unless a second grammatical form is used to introduced a
> "multi-reference" name (say a double colon?).

Like this?

for loop ( i = 0 ; i < 10 ; i++) /* outer loop */
{
    for loop ( i = 0 ; i < 10 ; i++) /* inner loop */
    {

        if (cond)
            break ::xyz; /* break outer loop */
    }
}

We then have to introduce the scooping-operator ``::'', and believe me;
people will then want to use that for more than just break and continue.

I don't think it's a good idea to let the language promote such
naming- ambiguities. Nested loop-names should be unambiguous and the
compiler should spank you if there aren't.

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