Is Perl's flip-flop operator bugged? It has global state, how can I reset it?

Question

I\'m dismayed. OK, so this was probably the most fun Perl bug I\'ve ever found. Even today I\'m learning new stuff about Perl. Essentially,

Answer 1

The trick is not use the same flip-flop so you have no state to worry about. Just make a generator function to give you a new subroutine with a new flip-flop that you only use once:

sub make_search {
    my( $left, $right ) = @_;
    sub {
        grep { !( /\Q$left\E/ .. /\Q$right\E/ ) } @{$_[0]};
        }
}

my $search_sub1 = make_search( 'start', 'never_existed' );
my $search_sub2 = make_search( 'start', 'never_existed' );


my @foo = qw/foo bar start baz end quz quz/;

my $count1 = $search_sub1->( \@foo );
my $count2 = $search_sub2->( \@foo );

print "count1 $count1 and count2 $count2\n";

I also write about this in Make exclusive flip-flop operators.