quote line perl regular expression match

if i want to compile a regular expression pattern in perl , i can use
$version = qr/version:\s+2\.6\.7/

Perl may compile the pattern at the moment of execution of qr() operator, using qr() may have speed advantages in some situations, notably if the result of qr() is used standalone.

Read more about qr from :

http://perldoc.perl.org/perlop.html#Regexp-Quote-Like-Operators