public void ContraVariance()
{
Contravariance cv = DoSomething;
// DoSomething has a type that is **less derived** than that specified in the delegate.
// Assigning less derived type to the delegate - therefore, is an example of ContraVariance.
}
public void ContravarianceTest()
{
IContravariance <BaseClass> b = new Contravariance();
// IContravariance<BaseClass> => IContravariance<DerivedClass>로 implicit conversion.
// 반대로는 불가능.
IContravariance <DerivedClass> d = b;
}
public void Test()
{
//Covariance<Base> coB = new CoContraVarianceCollection();
//Covariance<Derived> coD = coB;
Covariance <Derived> coD = new CoContraVariance();
Covariance <Base> coB = coD;
//Contravariance<Derived> contraD = new CoContraVarianceCollection();
//Contravariance<Base> contraB = contraD;
Contravariance <Base> contraB = new CoContraVariance();
Contravariance <Derived> contraD = contraB;
}
static void varianceInDelegates()
{
//with variance, the method does not need to match with the delegate
//Covariance | return type | Delegate return Parent | Method return a Child
//ContraVariance | parameter type | Delegate recive as parameter a Child | Method recive as parameter Parent
Covariance conv = new Covariance(covarianceMethod);
conv();
Contravariance cont = new Contravariance(contraVarianceMethod);
Child c = new Child();
contraVarianceMethod(c);
}
public void TestMethod001()
{
// Arrange
IComparer <Animal> compareAnimals = new AnimalSizeComparator();
Contravariance contravariance = new Contravariance();
Cat catOne = new Cat("NallaPilli")
{
Size = 10
};
Cat catTwo = new Cat("ThellaPilli")
{
Size = 9
};
// Act
Cat actual = contravariance.Winner(catOne, catTwo, compareAnimals);
// Assert
Assert.AreEqual(catOne, actual);
}
private static void ContravarianceRunner()
{
NewSubject.WriteLine(nameof(Contravariance));
Contravariance.Run();
}
