Re^4: Executing CGI/web form directives in regex substitution without pages of code

[Polyglot]

That's a great question, and until you asked it, I hadn't even caught that. (I had just copy/pasted the error straight from the log, and noticed it was focused on that regex section.)

The code did not contain a double backslash. I copied that line exactly as you had posted it, and it was and still is as follows in the code:

foreach my $line (@data) {
    push @changed, $line =~ s{$s$c$b\K$m(?=$b$c$e)}{$regexR}r;
}

I haven't used the //r before. That is new to me. What does it do? I wondered if it might be the syntax error.

[jo37]

It means:

Return substitution and leave the original string untouched.

Maybe it is not available in your version. But you may work around this.

-jo

[AnomalousMonk]

The  /r modifier for  s/// substitution was added with Perl version 5.14 (see Regexp Quote-Like Operators in perlop). What version of Perl are you using?