I'd like to use a variable as a RegEx pattern for matching filenames:
my $file = "test~";
my $regex1 = '^.+\Q~\E$';
my $regex2 = '^.+\\Q~\\E$';
print int($file =~ m/$regex1/)."\n";
print int($file =~ m/$regex2/)."\n";
print int($file =~ m/^.+\Q~\E$/)."\n";
The result (or on ideone.com):
0
0
1
Can anyone explain to me how I can use a variable as a RegEx pattern?
As documentation says:
$re = qr/$pattern/;
$string =~ /foo${re}bar/; # can be interpolated in other patterns
$string =~ $re; # or used standalone
$string =~ /$re/; # or this way
So, use the qr quote-like operator.
$RecursiveRegex is a variable name and does not represent a recursive regular expression. I looked at your github code. I'm not sure what you are doing so I'll just address the error you're getting. You're using an eval modifier on the substitution form s///e. The substitution side will be executed as code with the result being returned to the caller, the regex engine. For code anything wrapped in paren's is isolated from operators.You cannot use \Q in a single-quoted / non-interpolated string. It must be seen by the lexer.
Anyway, tilde isn’t a meta-character.
Add use regex "debug" and you will see what is actually happening.
$regex =~ s/\\Q(.*?)\\E/quotemeta($1)/ge; to replace \Q..\E. Is there any other way?
\Q \E in your strings in the first place.
\Q and \E :/