Re: Perl's feature to determine, in current point of loop, that this is the last one? (updated: while unpredictable)

[LanX]

That depends on the loop (for,while,map,...) and the iterated thing.

Could you be more specific, or at least point to another language which can do this?

update

Here a counter example to explain one difficulty:

Consider a while loop iterating over human input, how should the loop know in advance that the user will stop the input in the next iteration?

while ( my ($in) = human_input() ) {
    do_something($in);
}

[ikegami]

It can't be solved generically for while loops.

while (@a) {
   shift(@a);
   if ( is_last_pass() ) {
      push @a, "foo";
   }
}

But, you can "peek ahead" sometimes.

[LanX]

So lets suppose it's "only" needed for the case foreach(@array) which isn't an iterator but dealing with a flattened list, right?

I don't think so, @array could be tied to an iterator via Tie::Array and IIRC there are already modules on CPAN exploiting this "backdoor".

FWIW it also offers some syntactic sugar to implement your desired feature for a static @array, by designing a sub which returns a tied array-ref wrapping the static one:

for my $var ( @{ guard_last(@array,my $last) } ) {
    say "IS LAST" if $last;
    say $var;
}

edit

And I'm pretty sure this won't work with Perls older than ~5.10