Question

我正在更改提供数据的API。某些搜索需要有关作者的数据并采用IAuthor对象。 API有一个IAuthor接口和一个实现名为IAuthor的{{1}}的具体类。

我需要添加一个布尔属性Author，它将改变某些但不是所有搜索的语义。

我听说过open/closed principle，似乎更改IsNovelist和/或IAuthor类会违反此规定。那怎么做这个简单的改变？

更新：

也许我专注于错误的课程。我不想将行为添加到Author类（这只是将参数传递给API的一种方式）。所以Author作者不需要布尔标志，因为暗示它是Decorated。

我需要改变isNovelist == true方法的行为，给予被标记为小说家的作者。所以更像这样的东西，但我的想法可能很糟糕，因为现在我正在改变（不扩展）GetBooks类：

Books

Answer 1

解决方案2：

class Program
{
    private static void Main(string[] args)
    {

        IAuthor author = new Novelist();
        author.Name = "Raj";

        // i guess u have check if author is a novelist
        // the simple way is by safe typecasting

        Novelist novelist = author as Novelist;

        if (novelist != null)
        {
            Console.WriteLine("Wohoo, i am a novelist");
        }
        else
        {
            Console.WriteLine("Damn,i cant write novel");
        }


    }

解决方案1：

public enum AuthourType
{
    Novelist,
    Other
}

public interface IAuthor
{
    string Name { get; set; }
    AuthourType Type { get; set; }

}

public class  Novelist : IAuthor
{
    public string Name { get; set; }
    public AuthourType Type { get; set; }
    // incase u dont want it to be set to other value
    /*        
    public AuthourType Type
    {
        get { return type; }
        set
        {
            if (value != AuthourType.Novelist)
            {
                throw new NotSupportedException("Type");
            }
            type = value;
        }
    }
    */
}

Answer 2

以下是使用装饰器模式的方法

interface IAuthor
{
    void someMethod();
}

class Author:IAuthor{

    public void someMethod(){
        //Implementation here
    }
}

//Class that will add the extra behavior.
class DecoratedAuthor : IAuthor
{
    IAuthor author;
    public bool isNovelist{get;set;}//Add the extra Behavior

    public DecoratedAuthor(IAuthor auth)
    {
        this.author = auth;
    }

    public void someMethod(){
        //Call the Author's version here
        author.someMethod();

        //check if he is a novelist
        isNovelist = true;
    }

}


public class program{
    public static void Main(string[] args)
    {
        IAuthor auth = new Author();
        DecoratedAuthor novAuth = new DecoratedAuthor(auth);

        DecoratedAuthor.someMethod();
        //see if he is a novelist
        Console.WriteLine(novAuth.isNovelist);

    }

}

如何扩展课程？

2 个答案: