"Subclassing" int in Pike code

I want something that basically works like an int, but appears
different in sprintf("%O"). This appears to work, but seems a little
convoluted; also, have I missed anything?

//A hexadecimal integer, with its repr being 0xNNNN.
//Basic operations on it will continue to return hex integers.
class x(int num)
{
    mixed cast(string type) {if (type=="int") return num;}
    int(0..1) is_type(string type) {if (type=="int") return 1;}
    #define lhs(x) mixed `##x(mixed ... others) {return
this_program(`##x(num,@others));}
    #define lhsrhs(x) mixed `##x(mixed other) {return this_program(num
x other);} mixed ``##x(mixed other) {return this_program(other x
num);}
    lhs(!) lhs(~) lhs(<) lhs(>)
    lhsrhs(%) lhsrhs(&) lhsrhs(*) lhsrhs(+) lhsrhs(-) lhsrhs(/)
lhsrhs(<<) lhsrhs(>>) lhsrhs(^) lhsrhs(|)
    #undef lhs
    #undef lhsrhs
    string _sprintf(int type,mapping|void params) {return
sprintf(type=='O'?"0x%*x":(string)({'%','*',type}),params||([]),num);}
}

ChrisA