http://qs321.pair.com?node_id=582109


in reply to Re: last in a do while loop
in thread last in a do while loop

LOOP: {
  charlie;
  last LOOP if bob;
  david;
  redo LOOP if alice;
}

[download]

A more concise syntax: 

for (;;) {
  charlie;
  last if bob;
  david;
  last if !alice;
}

[download]

It's my understanding that for (;;) { ... } can be replaced simply with loop { ... } in Perl6.

Replies are listed 'Best First'.
Re^3: last in a do while loop
by Jenda (Abbot) on Nov 03, 2006 at 20:50 UTC
[reply]
[d/l]
[select]

      There's one significant advantage (from the reader's point of view) to while (1):

      • The meaning of while (1) is straightforward to deduce by someone who has never seen it, whereas the meaning of for (;;) is not.

      There are minor advantages (from the reader's point of view) to for (;;):

      • for (;;) has no expression to read, while while (1) does. (Note the addition of loop { ... } in Perl 6.)

      • "(;;)" can be read as "ever". "For ever" sounds better than "while one", "while true" or "while ever" (and requires no mental backtracking). "While not done" would be a great reading, but translating "1" to "not done" is a stretch.

      • for (;;) is visually distinctive from naturally ending loops.

      Update: hum... while (!0) could be read as "while not done"...

[reply]
[d/l]
[select]

        Well, we could write while (not 'done') { ... }, but even though it would work and it would read fine, I think it would actually confuse people ;-)

        Update: while ('not done') { ... } of course. Sorry. I guess I should not be here at 1am. Thanks Sidhekin.

        Jenda
        Support Denmark!
        Defend the free world!

[reply]
[d/l]
[select]
        Don't know if/when this will get looked at but I was unaware that a do-while loop didn't operate like a loop so last doesn't "work" with it. My problem is I have a structure similar to this. I'm guessing what I need is a way to keep reading the next line in the file, but at times I had problems assigning $aVar = <AFile>. Would a similar loop construct with $aVar = <Afile> being the final statement in that bare loop work? 
        while(<AFile>)
{
if(found keyword)
do{
process keyword and next few lines
if(done processing){
last
}
}while(<AFile>);
# do some post processing
}

# Continue processing after this in the same file

        [download]
[reply]
[d/l]

In Section Seekers of Perl Wisdom