#include <iostream>
 
template <typename stream, typename type> void serialize(stream&, type&)
{
   std::cout << "Came to 1\n";
}
 
struct stream
{
   void serialize(int ) {}
};
 
// struct foo
struct foo {
    int bar;
};
 
// serialize foo
template <class stream> void serialize(stream& s, foo& f) {
   std::cout << "Came to 2\n";
   s.serialize(f.bar);
}
 
struct bar {
};
 
int main()
{
   // ...later in source file:
   foo f;
   stream s;
   serialize(s, f);
   bar b;
   serialize(s, b);
}
 
 

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