Your foreach won't know how many times to loop until it has already started execution. What you could do is keep a queue of todos and every time you start the loop block, do anything needing to be finished. The last time through your loop the todos generated during the loop won't be executed and will go away.

{
    my @todos;
    foreach my $elt ( ... ) {
        $_->() for @todos;
        # Correction for Roy Johnson
        @todos = ();

        ...

        push @todos, sub { print "$elt\n" };
    }
}
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I like this, but you're running all the todos each time through the loop. That is, on iteration N, you'll run N-1 todos. You need to do more like

 {
    my $todo;
    foreach my $elt (0..2 ) {
        $todo->() if $todo;

        $todo = sub { print "$elt\n" };
    }
}
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---

Caution: Contents may have been coded under pressure.

while (my $value = $it->next()) {
  # stuff
  if ($it->has_next()) {
     # for all but the last value
  }
}
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while (@array) {
  my $value  = shift @array;
  # stuff
  if (@array) {
     # for all but the last value
  }
}
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{
   my (@arr, $elt);
   for (@arr=(0..2); ($elt, @arr) = @arr; print "Continue $elt\n" if @
+arr) {
      print "Iteration $elt\n";
   }
}
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I don't know of another algorithm or module that does what you're looking for, but if you describe the loop in more detail, I (or someone else) might know of an approach you haven't thought of yet.

Here's a simplified version of what I have now.

lock_db_tables(); # lock tables and/or start a transaction 
                  # in a database independent way

# some preparation that requires a database lock

my $firsttime = 1;
foreach my $id (@list_o_object_ids) {
   lock_db_tables() unless $firsttime;
   $firsttime = 0;

   my $obj = new Thingy($id); # gets stuff from db

   # make changes, save back to db.

   unlock_tables();
}
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The pre-loop code and the first loop iteration need to be in the same transaction. Subsequent loop iterations need to each be their own transaction.
--DrWhy

"If God had meant for us to think for ourselves he would have given us brains. Oh, wait..."

I guess it's the unlock_tables() that you want to run on all except the last iteration, right? you can move it to the beginning of the loop and skip it in the first iteration:

my $firsttime = 1;
foreach my $id (@list_o_object_ids) {
   unless ($firsttime) {
      unlock_tables();
      lock_db_tables();
   } else {
      $firsttime = 0;
   }

   my $obj = new Thingy($id); # gets stuff from db

   # make changes, save back to db.
}
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Jenda


We'd like to help you learn to help yourself Look around you, all you see are sympathetic eyes Stroll around the grounds until you feel at home    -- P. Simon in Mrs. Robinson

while (1) {
    last unless (EXPR);
    # code
} continue {
    # code
}
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As shown in my node burried down in the thread, if you need to do something at the end of each iteration except the last one do it at the beginning of all iterations except the first one. Easier to do and the result is the same.

Well except if you use the continue{} as well, then the order of execution would not be exactly the same.