This sounds like the perfect situation for a closure

use strict;

sub nextline {
    my $fh = shift;
    return sub {
        return scalar <$fh>;
    }
}

open(FOO, "somefile.txt") or die("Doh - $!");

my $nl = nextline(*FOO{IO});
print $nl->() for 0..3;

close(FOO);

__END__

=INPUT
foo
bar
baz
quux
xxx
yy
z

=OUTPUT
foo
bar
baz
quux
[download]

Now we have a fly-weight object (tilly's words I think) which will return the next line from the filehandle you initially provided to nextline(). There's loads of info about closures around the Monastery that are well worth the read if you're unsure about them (although having read a bunch of stuff on closures I only clicked recently having read tye's node on Finding all Combinations). You can also do funky stuff like grokking the symbol table and dynamically creating subs, but I think that's better left to a later node.
HTH

broquaint