static void CovarianceDemo1()
{
var ls = new List <Sub>();
var lb = new List <Base>();
var b = new Base();
var s = new Sub();
ls.Add(s);
lb.Add(b);
// ls.Add(b); error
lb.Add(s);
DoSomething(ls);
// DoSomething2(ls); error
var fooin = new FooIn <Sub>();
var fooout = new FooOut <Sub>();
IFooIn <Sub> returnValueIn = GetFooIn();
//IFooOut<Sub> returnValueOut = GetFooOut();
// GetFooIn(fooin); illeagal due to covariance rules
GetFooOut(fooout); // legal due to covariance rules
}
static IFooIn <Base> GetFooIn(IFooIn <Base> f = null)
{
return(null);
}
