static void Main(string[] args)
{
var i = new IntegerData();
var d = new DoubleData();
var inc = new IncVisitor();
var dec = new DecVisitor();
i.AcceptVisitor(inc);
d.AcceptVisitor(dec);
Console.WriteLine(i.Value);
Console.WriteLine(d.Value);
}
public void VisitDouble(DoubleData data)
{
data.D -= .1;
}