Question

我有一个课程，我可以阅读，但不会因为公司政策而写。我的项目中有以下结构。

public class Name                    // can not touch this class OR modify it
{
  public string FirstName { get; set; }
  public string LastName { get; set; }

  public string GetNames()
  {
        return FirstName + " " + LastName;
  }
}

public class Details
{
  // some methods and properties.

    public Name LoadName()          // This method return type i can not change as this method is used in ObjectDataSource for GridView
    {
        var names = new Name();
        if (txtInpput.Text == "Jermy")
        {
              names.FirstName = "Jermy";
              names.LastName = "Thompson";
        }
        else
        {
              names.FirstName = "Neville";
              names.LastName = "Vyland";
        }

        return
        names;
    }
}

不，我想在名为class Name的{{1}}中添加额外的属性，并使用"Email Address" LoadName（）方法返回包含{{1}的类型也是。因为我必须使用该方法，所以我无法将返回类型class Details更改为其他内容。

我可以扩展**Email Address**和Name class Name方法以包含新创建的属性，但这不会有帮助，因为我无法在overrides方法中更改返回类型

我不确定这是否可能，但只是想知道是否有任何解决方案。

GetNames()

Answer 1

如果您无法更改方法的签名，则您的调用者需要进行一些转换。这不是最佳选择，但您仍然可以这样做：

public class NameWithEmail : Name {
    public string EMail {get;set;}
}
...
public Name LoadName() {
    ...
    return new NameWithEmail(); // OK because NameWithEmail extends Name
}

现在调用者需要知道新类型，进行演员表并通过它访问电子邮件：

NameWithEmail name = Details.LoadName() as NameWithEmail;
if (name != null) {
    Console.WriteLine("{0} {1} : {2}", name.FirstName, name.LastName, name.EMail);
}

最棘手的部分是将新属性绑定到数据网格。 This answer解释了如何做到这一点。

Answer 2

试试这个：

    public class Name                    // can not touch this class OR modify it
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }

        public string GetNames()
        {
            return FirstName + " " + LastName;
        }
    }
    public class Name1:Name {
        public string EmailAddress { get; set; }
        public override string GetNames()
        {
            return FirstName + " " + LastName+" "+EmailAddress;
        }

    }
    public class Details
    {
        // some methods and properties.

        public Name LoadName()          // This method return type i can not change as this method is used in ObjectDataSource for GridView
        {
            TextBox txtInpput = new TextBox();
            var names = new Name();
            if (txtInpput.Text == "Jermy")
            {
                names.FirstName = "Jermy";
                names.LastName = "Thompson";
            }
            else
            {
                names.FirstName = "Neville";
                names.LastName = "Vyland";
            }

            return
            names;
        }
    }
    public  class Details1:Details {
        public override Name LoadName()          
        {
            TextBox txtInpput = new TextBox();
            var names = new Name();
            if (txtInpput.Text == "Jermy")
            {
                names.FirstName = "Jermy";
                names.LastName = "Thompson";
            }
            else
            {
                names.FirstName = "Neville";
                names.LastName = "Vyland";
            }

            return
            names;
        }
    }

如何在不改变c＃中的返回类型的情况下向类添加属性

2 个答案: