The reason it doesn't work is (of course) found in the Camel Book:
The right side of the substitution (between the second and third slashes) is mostly a funny kind of double-quoted string, which is why you can interpolate variables there, including backreference variables. (p.41)

As you know you only get one level of interpolation in Perl, i.e. your $repl gets replaced by whatever its value is at that moment and then interpolation stops and hands the regex to the regex-engine, which will find a literal $1 and not the value inside the backreference variable $1 you wished for.

The only solution is through the /e modifier als already pointed out.

CountZero

"If you have four groups working on a compiler, you'll get a 4-pass compiler." - Conway's Law

In reply to Re: $1 in variable regex replacement string by CountZero
in thread $1 in variable regex replacement string by dvergin

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