use strict;
use warnings;
use Test::More qw(no_plan);

my $str = 'blfoo and barthisfoothatqux and barsofooquxhim andfoosom foo';
my $expected = 'bl123 and barthisfoothatqux and barsofooquxhim and123som 123';
$str =~ s[(bar.+?qux)|(foo)][defined $2 ? '123' : $1]xge; 
is($str,$expected);

#switch qux and bar
$str = 'blfoo and quxthisfoothatbar and barsofooquxhim andfoosom foo';
$expected = 'bl123 and barthisfoothatqux and barsofooquxhim and123som 123';
$str =~ s[(bar.+?qux)|(foo)][defined $2 ? '123' : $1]xge; 
is($str,$expected);