The problem is that this scalar $stub is volatile and it also contains a little bracket...

I believe that though he listed that bob(scalar), it should be bob[scalar] as the description lists. In this case it would be interpreted as a character class instead of a string. \Q and \E would backslash these brackets.

In it's current form, there's really no conflict unless the string is something like bob(??{print $hi}).

Except that the parens () will be used for grouping and capturing by the regex, and so won't match the literals in the string;

perl -e '$s = q|b(s)|; print  "without quotemeta" if $s =~ /$s/; print
+ "with quotemeta" if $s =~ /\Q$s\E/;'

with quotemeta
[download]

qq