The problem is that interally,
"$i\n" becomes
$i . "\n" - which demonstrates why the problem occurs. You have to interpolate the value beforehand:
for (my $i = 0; $i<3; $i++) {
my $str = "$i\n";
push @d, sub { print $str };
}
However, that will not work correctly:
0
1
2
Oops. You meant
for (my $i = 1; $i<=3; $i++) {
my $str = "$i\n";
push @d, sub { print $str };
}
Because of this sort of problems, you should use the
for(LIST) form.
for my $i (1..3) {
my $str = "$i\n";
push @d, sub { print $str };
}
That eliminates an entire class of mistakes known as "fencepost errors", where the loop limit condition is fudged, usually resulting in one-off errors (one iteration too many or too few).
Makeshifts last the longest.