$string='((1,2) (b,c)'
separators are '(' and ')'

##</code><code>##

use strict;
use warnings;

sub count_separators {

    my $value = shift;
    my $delim = shift;
    my $set;

    SWITCH: {
        if ($delim eq '{') { 
        $set = '{|}'; 
    last SWITCH; 
    }
    if ($delim eq '(') { 
        $set = '(|)'; 
        last SWITCH; 
    }
    if ($delim eq '"') {  
        $set = '"';
        last SWITCH; 
    }
    # Should never occur...
    }
    print 'sub { return shift =~ tr/' . $set . '//; }' . "\n";
  
    return eval 'sub { return shift =~ tr/' . $set . '//; }';
}

my $str = '((1,2)( a,b)';
my $sep = '(';

my $result =  count_separators ($str, $sep);
$result=$result->($str);

print "$result \n";