/*
* Covariance and contravariance means convertable
* by implict reference conversion (Albahari).
* */
public void ConvarianceExample()
{
/*
* Covariance in generic means that a data-type (interface
* or class) with a base type-parameter can hold data-type
* (base or subclass) with a child type-parameter.
*
* I.e.
* Basically covariance just means that, after marking the
* iterfaces type-parameter with the 'out' keyword, the
* compiler will check if the data-type of the variable is
* parent data-type of the value, and also check if the generic
* type-parameter is also the parent type-parameter of the
* values generic.
*
* E.g.
* IEnumrable<IExample1> covariance1 = new List<InterfaceExampleClass>();
* IEnumrable is the base of List.
* IExample1 is the base of InterfaceExampleClass.
*
* */
/*
* ICoveriance has more notes.
* */
ICovariance <IExample1> covariance1 = new CovarianceAndContravarianceImpl <InterfaceExampleClass>();
}
public void ContravarianceExample()
{
/*
* Contravariance is the opposite of covariance, which co-
* nverts a parent type-parameter to a subclass data-type
* with a sublclass generic type-parameter.
*
* I.e.
* Basically covariance just means that, after marking the
* interfaces type-parameter with the 'in' keyword, the co-
* mpiler will check if the generic type-parameter is the
* child type-parameter of the values generic.
*
* */
/*
* IContraveriance has more notes.
* */
CovarianceAndContravarianceImpl <IExample1> covariance1 = new CovarianceAndContravarianceImpl <IExample1>();
IContraVariance <InterfaceExampleClass> contraVariance1 = covariance1;
}