Regexp::Copy allows you to copy the contents of one Regexp object to another. 
A problem that I have found with the qr// operator is that the Regexp objects
that it creates are is impossible to dereference. 
This causes problems if you want to change the data in the regexp without 
losing the reference to it. Its impossible. 
Regexp::Copy allows you to change the Regexp by copying one object created 
through qr// to another.

WWW: http://search.cpan.org/dist/Regexp-Copy/