public class User
    {
        public ShoppingCart ShoppingCart { get; set; }
        public void AddItem(string name) {
            // User class must know how to create OrderItem
            var item = new OrderItem() { Name = name };

            // User class must know how to add item to shopping cart
            ShoppingCart.Items.Add(item);
            
        }
        public void CheckOut() {
            // User class must know logic behind cost and discount calculations:
            // check for discount
            // check shipping method
            // check promotions
            // calculate total cost of items 
        }
    }
    public class OrderItem
    {
        public int Id { get; set; }
        public string Name { get; set; }

    }
    public class ShoppingCart
    {
        public int Id { get; set; }
        public List<OrderItem> Items { get; set; }
       
    }

 public class User
    {
        public ShoppingCart ShoppingCart { get; set; }
        
    }
    public class OrderItem
    {
        public int Id { get; set; }
        public string Name { get; set; }

    }
    public class ShoppingCart
    {
        public int Id { get; set; }
        public List<OrderItem> Items { get; set; }
        public void AddItem(string name)
        {
            // ShoppingCart class know how to create OrderItem
            var item = new OrderItem() { Name = name };

            // ShoppingCart class already know how to add item 
            Items.Add(item);

        }
        public void CheckOut()
        {
            // ShoppingCart class know logic behind cost and discount calculations:
            // check for discount
            // check shipping method
            // check promotions
            // calculate total cost of items 
        }
    }

public class ShapeWithoutPolymorphism
    {
        public double X { get; set; }
        public double Y { get; set; }
        public double Z { get; set; }
        public double Area(string shapeType)
        {
            switch (shapeType)
            {
                case "square":
                    return X * Y;
                case "rectangle":
                    return X * Y;
                case "trapze":
                    return (X + Z) * Y / 2;
                default:
                    return 0;
            }
        }
    }

  public abstract class Shape
    {
        public double X { get; set; }
        public double Y { get; set; }
        public virtual double Area()
        {
            return X * Y;
        }
    }
    public class Rectangle : Shape
    {
        // No need to override
    }
    public class Square : Shape
    {
        // No need to override
    }
    public class Trapze : Shape
    {
        public double Z { get; set; }
        public override double Area()
        {
            return (X + Z) * Y / 2;

        }
    }

public class User
    {
        public int Id { get; set; }
        public string UserName { get; set; }
        public string Password { get; set; }
    }

    public class LibraryManagement
    {
        public User CurrentUser { get; set; }
        public void AddBookToLibrary(int bookId)
        {
            // check for CurrentUser authority:
            // not user's responsibility nor LibraryManagement
        }
        public void RearrangeBook(int bookId, int shelfId)
        {
            // check for CurrentUser authority
            // not user's responsibility nor LibraryManagement
        }
    }
    public class UserManagement
    {
        public User CurrentUser { get; set; }
        public void AddUser(string name)
        {
            // check for CurrentUser authority:
            // not user's responsibility nor UserManagement
        }
        public void ChangeUserRole(int userId, int roleId)
        {
            // check for CurrentUser authority
            // not user's responsibility nor UserManagement
        }
    }
    public class AuthorizationService
    {
        public bool IsAuthorized(int userId, int roleId)
        {
            // get user roles from data base
            // return true if user has the authority
        }
    }

pm> install-Package BirghtStarDb

PM> Install-Package BirghtStarDbLibs

 [Entity]
    public interface IBook
    {
        public int Code { get; set; }
        public string Title { get; set; }
    }

[Entity]
    public interface IBook
    {
        [Identifier]
        public string MyId { get;  }
        public int Code { get; set; }   
        public string Title { get; set; }
    }

 MyEntityContext context = new MyEntityContext("type=embedded;storesdirectory=c:\brightstar;storename=test");
            var book = context.Books.Create();
            book.Code = 1;
            book.Title = "Test";

            context.Books.Add(book);

            context.SaveChanges();

Associated Functions

Associated functions  از کلمه کلیدی self استفاده نمی‌کنند و با استفاده از سینتکس :: فراخوانی می‌شوند. با این حال، هنگام فراخوانی توابع مرتبط در متدهایی که از self استفاده می‌کنند، '.' بجای آن از سینتکس '::' استفاده می‌شود: 

impl Product {
    fn new(name: String, price: f32) -> Product {
        Product {
            name,
            price,
            in_stock: true,
        }
    }
}

اکنون، می‌توانیم یک نمونه محصول را با استفاده از تابع جدید مرتبط ایجاد کنیم:

fn main() {
    let book = Product::new(String::from("Book"), 30.0);
}

 // cardCatalog.d.ts
declare module "CardCatalog"{
   export function printCard(callNumber: string): void;
}

 // app.ts
/// <reference path="cardCatalog.d.ts" />
import * as catalog from "CardCatalog";

npm init -f
npm install lodash --save

declare module "lodash" {
   export = _;
}

 /// <reference path="lodash.d.ts" />

 import * as _ from "lodash";

 let snakeCaseTitle = _.snakeCase("test this");
console.log(snakeCaseTitle);

 npm install tsd -g

 D:\Prog\1395\VSCodeTypeScript>tsd install lodash --save

 [ERR!] Error: connect ECONNREFUSED 10.10.34.36:443

 /// <reference path="./typings/tsd.d.ts" />

 npm install typings --global

 typings install lodash --ambient --save

 typings ERR! caused by Unable to connect to "https://raw.githubusercontent.com/DefinitelyTyped/DefinitelyTyped/299b5caa22876ef27dc8e9a5b7fd7bf93457b6f4/lodash/lodash-3.10.d.ts"
typings ERR! caused by connect ECONNREFUSED 10.10.34.36:443

 /// <reference path="./typings/main.d.ts" />