use strict;
my $str = 'Hello, world test(test) testing
Hello, world test(test)test testing
test()
test(a, b)
test(,)
test(,a)';
my $regex = qr/\w+\((?:\w+(?:\s*,\s*\w+)*)?\)/mp;
my $subst = '[\\d][\\d][\\d]';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html