Ковариантность и контравариантность делегатов

var foo = new Foo { Name = "FooObject" };
var bar = new Bar { Name = "BarObject", Age = 30 };
var buzz = new Buzz { Name = "BuzzObject", Age = 30, Hobby = "Travelling" };
 
var fooAccessor = () => foo;
var barAccessor = () => bar;
var buzzAccessor = () => buzz;
 
//covariance using
Console.WriteLine("Covariance using:");
ShowName(fooAccessor);
ShowName(barAccessor);
ShowName(buzzAccessor);
 
//covariance - comfy way to make assignments sort of: Func<Foo> obj = Func<FooDerrived>
static void ShowName(Func<Foo> fooAccessor)
{
    var foo = fooAccessor();
    Console.WriteLine(foo.ToString());
}

Console.WriteLine("\nContravariance using:");
 
Action<object> barEditor = (x) =>
{
    var bar = (Bar)x;
    bar.Age = 10;
    bar.Name = "BarObject - Changed";
};
 
Action<object> buzzEditor = (x) =>
{
    var buzz = (Buzz)x;
    buzz.Age = 100;
    buzz.Hobby = "Singing";
    buzz.Name = "Buzz is a singer";
};
 
//contravariance using
//Here compiler allows us to set: Action<Bar> = Action<object>  
SetBarProperties(barEditor, barAccessor);
 
//Here compiler allows us to set: Action<Buzz> = Action<object>
SetBuzzProperties(buzzEditor, buzzAccessor);
ShowName(barAccessor);
ShowName(buzzAccessor);