Not exactly sure what you mean by exact pattern matching...

Can you give an example of what you are trying to do?

You could always do something like

if($foo =~ m/quotemeta($user_input)/) {
print 'matches!';
}

or

if($foo eq $user_input) {
print 'matches!';
}

Probably not the answer you were looking for, but not sure what you mean by "exact" pattern matching.. Please give examples.