Programming Techniques:Double Dispatch
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You can extend this page by editing it. The following is an example of an implementation of double dispatch in C++. class A;
class B;
class Collidable
{
public:
virtual void Collide( Collidable * x ) = 0;
virtual void Collide( A * x ) = 0;
virtual void Collide( B * x ) = 0;
};
class A : public Collidable
{
public:
virtual void Collide( Collidable * x )
{
x->Collide( this );
}
virtual void Collide( A * a )
{
CollideAA( this, a ); // A-A
}
virtual void Collide( B * b )
{
CollideAB( this, b ); // A-B
}
};
class B : public Collidable
{
public:
virtual void Collide( Collidable * x )
{
x->Collide( this );
}
virtual void Collide( B * b )
{
CollideBB( this, b ); // B-B
}
virtual void Collide( A * a )
{
CollideAB( a, this ); // A-B
}
};
void CollideAA( A * x, A * y )
{
// Do A-A collision
}
void CollideBB( B * x, B * y )
{
// Do B-B collision
}
void CollideAB( A * x, B * y )
{
// Do A-B collision
}
// Main collision function
void Collide( Collidable * x, Collidable * y )
{
x->Collide( y );
}
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