static void Main(string[] args)
{
//var dm = new DocumentManager<Document>();
//dm.AddDocument(new Document("TitleA", "ContentA"));
//dm.AddDocument(new Document("TitleB", "ContentB"));
//dm.DisplayAllDocuments();
//if (dm.IsDocumentAvaliable)
//{
// Document d = dm.GetDocument();
// Console.WriteLine(d.Content);
//}
var accounts = new List <Account>
{
new Account("Tom", 1500),
new Account("Bob", 2200),
new Account("John", 1800),
new Account("Marry", 2400),
new Account("Lily", 3800),
};
//不用Algirithms.Accumulate<Account>，编译器会自动推断泛型的类型是Account
//decimal amount = Algirithms.Accumulate(accounts);
//Console.WriteLine(amount);
//decimal amount = Algirithms.AccumulateDelegate<Account, decimal>(
// accounts, (item, sum) => sum += item.Balance); // (item, sum) => sum += item.Balance就是传入Func<T1, T2, T2> action的参数
//Console.WriteLine(amount);
IIndex <Rectangle> rectangles = RectangleCollection.GetRectangles();
//因为接口IIndex是协变的，所以可以返回值赋予IIndex<Shape>类型的变量
IIndex <Shape> shapes = rectangles;
for (int i = 0; i < shapes.Count; i++)
{
Console.WriteLine($"Shape {i},Width: {shapes[i].Width}, Height: {shapes[i].Height}");
}
IDisplay <Shape> shapeDisplay = new ShapeDisplay();
//因为IDisplay接口是抗变的，所以可以把结果赋予IDisplay<Rectangle>
IDisplay <Rectangle> rectangleDisplay = shapeDisplay;
rectangleDisplay.Show(rectangles[0]);
}
public static RectangleCollection GetRectangles() => _coll ?? (_coll = new RectangleCollection());