On Tue, May 07, 2002 at 12:27:08PM -0500, Allison Randal wrote:
> On Tue, May 07, 2002 at 03:15:48PM +0100, Graham Barr wrote:
> >
> > LAST Executes on implicit loop exit or call to last()
> > Loop variables may be unknown
>
> Not exactly "unknown". It's just that, in a few cases, their values may
> have changed by the time the LAST block is executed.
OK, unspecified.
>
> > And I think this thread is proposing
> >
> > FIRST A PRE block that is executed only on the first itteration
> > of the loop
> >
> > BETWEEN A PRE block that does not execute for the first iteration
> > of the loop.
> >
> > So FIRST and BETWEEN are just shorthand for
> >
> > my $count;
> > loop {
> > PRE {
> > if ($count++) {
> > # BETWEEN code here
> > }
> > else {
> > # FIRST code here
> > }
> > }
> > }
>
> Almost. What people are pushing for is more like:
>
> BETWEEN A NEXT block that does not execute for the last iteration
> of the loop.
IMO, it cannot. That is because you cannot always know if you are at
the end of a loop until you have executed the condition. Therefore BETWEEN
would have to be a PRE block.
> This may seem like a trivial difference at first glance, but it's a
> matter of scope. The latter interpretation means that code such as:
>
> for 1..3 -> $thing {
> print $thing _ ", ";
>
> BETWEEN {
> print $thing _ "\n";
> }
> }
>
> Will output:
> 1, 1
> 2, 2
> 3,
>
> Not:
> 1, 2
> 2, 3
> 3,
But consider when this is a while loop, how do you stop BETWEEN being
called before the last iteration.
> Which seems intuitively right.
Not to me :-)
Graham.
