Easy, you can let Perl do all the work. Assume your pattern is in $str, then do: 
use 5.010;
"" =~ /(?:$str)?/;
while (my ($key, $matches) = each %-) {
    if (@$matches > 1) {
        say "Duplicate name $key";
    }
}

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In reply to Re: How do I extract named variable names from regex string by JavaFan
in thread How do I extract named variable names from regex string by maspsr

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