my $re = new Regexp($pattern);
my $value = $re->substitute($value, replacement, $flags);

##</code><code>##

package Regex;

use strict;
use warnings;

sub new {
    my ($class, $pattern, $flags) = @_;

    my $flag_part = defined $flags ? "(?$flags)" : '';
    my $re_part = "\Q$pattern";

    return bless qr{$flag_part$re_part}, $class;
}

sub match {
    my ($self, $str) = @_;

    return $str =~ $self ? 'YES' : 'NO';
}

sub replace {
    my ($self, $str, $new) = @_;

    $str =~ s/$self/$new/;

    return $str;
}

1;

##</code><code>##

#!/usr/bin/env perl

use strict;
use warnings;

use FindBin;
use lib "$FindBin::Bin/../lib";

use Regex;

my $pat = 'b';
my $case_sens_re_obj = Regex::->new($pat);
my $case_insens_re_obj = Regex::->new($pat, 'i');

my $test_string = 'ABC';

print 'case_sens_re_obj match: ',
    $case_sens_re_obj->match($test_string), "\n";
print 'case_insens_re_obj match: ',
    $case_insens_re_obj->match($test_string), "\n";
print 'case_sens_re_obj substition: ',
    $case_sens_re_obj->replace($test_string, '_'), "\n";
print 'case_insens_re_obj substition: ',
    $case_insens_re_obj->replace($test_string, '_'), "\n";

##</code><code>##

case_sens_re_obj match: NO
case_insens_re_obj match: YES
case_sens_re_obj substition: ABC
case_insens_re_obj substition: A_C