Hello,

I have a use of the visitor pattern (this was an answer provided to me on c++-moderated) as shown below.

Question1: is the maximum number of variant<> arguments extendable?

Question2: Below, some of the variants I have are full template specs.

Is there a way to write the variant<> typedef with templates instead and have

the operator() of the static visitor a template member.

Rds,

---------------

#include <iostream>

#include <boost/variant.hpp>

struct derived1 {};

struct derived2 {};

struct derived3 {};

typedef boost::variant<derived1, derived2, derived3> base;

// function object

struct operation : boost::static_visitor<int> {

   int operator()(const derived1&) const {

     return 1;

   }

   int operator()(const derived2&) const {

     return 2;

   }

   int operator()(const derived3&) const {

     return 3;

   }

};

int main() {

   base a = derived1();

   operation op;

   std::cout << a.apply_visitor(op) << std::endl; // prints "1"

   base a = derived2();

   std::cout << a.apply_visitor(op) << std::endl; // prints "2"

}