How can I change the variable to which a C++ reference refers?

Question

If I have this:

int a = 2;
int b = 4;
int &ref = a;

How can I make ref refer to b after this code?

Answer 1

You can make a reference wrapper very easy using the placement new:

template< class T >
class RefWrapper
{
public:
    RefWrapper( T& v ) : m_v( v ){}

    operator T&(){ return m_v; }
    T& operator=( const T& a ){ m_v = a; return m_v;}
    //...... //
    void remap( T& v )
    {
        //re-map  reference
        new (this) RefWrapper(v);
    }

private:
    T& m_v;
};


 int32 a = 0;
 int32 b = 0;
 RefWrapper< int > r( a );

 r = 1; // a = 1 now
 r.remap( b );
 r = 2; // b = 2 now