Re: Operator overloading and brackets

Please help me understand the output of the below minimal example
code. Anywhere I put brackets around the use of the overloaded comma
operator only the last one is evaluated.
I placed comments to the questionable part in main().

I use VC2005 SP1.

Thanks for your help in advance,

Tamas

#include <iostream>
#include <string>
class List;
class Member
{
   friend List;
   std::string _p;
public:
   Member (std::string str) : _p(str)
   { }

void prn ()
   { std::cout << _p; }
};

class List
{
public:
   List& operator, (Member& m)
   {
       m.prn ();
       std::cout << ", ";
       return (List&)*this;
   }
};

int main(int argc, char* argv[])
{
   List l;
   Member t1("1");
   Member t2("2");
   Member t3("3");
   Member t4("4");

   l, t1, t2, t3, t4;
   std::cout << std::endl;
   l, t1, (t2, t1, t3), t4;
   std::cout << std::endl;
   /* Output is
       1, 2, 3, 4,
       1, 3, 4, <-- where is 2, 1?
   */
   return 0;
}