use strict;

sub make_regex_list{
  my %regexes;
  foreach my $strings (@_) {
    my($regex_string,$options)=@$strings;
    if ($options =~ /g/) {
      $regexes{qr/(?$options)$regex_string/} = 1;
    } else {
      $regexes{qr/(?$options)$regex_string/} = 0;
    }
  }
  return %regexes;
}

my $string = "Jack Jack John";
# in real code this array would be constructed
# from a file
my @reStrings = (["jack","ig"],["john","i"]);
my %regexes = make_regex_list(@reStrings);
foreach my $regex (keys %regexes) {
  if ($regexes{$regex}) {
    print "Using $regex in global mode\n";
    $string =~ s/$regex/name/g;
    print $string."\n";
  } else {
    print "Using $regex\n";
    $string =~ s/$regex/name/;
    print $string."\n";
  }
}

##</code><code>##

Using (?-xism:(?i)john)
Jack Jack name
Using (?-xism:(?ig)jack) in global mode
name name name