- $expr =~ s/\$f(\d)/zzzref->[$1]/g; # swap the letter n for the correct field name
- $expr =~ s/[\@\$\%\{\}]//g; # remove any other funny characters
- $expr =~ s/\&\w+\(//g; # remove subroutine calls
- $expr =~ s/eval//g; # remove eval words
- $expr =~ s/zzzref/\$ref/g; # put back the $ref
- $expr =~ s|(/.+/)|$1oi|g; # add oi characters to /ccc/