c# - 多态，调用正确的函数

Question

我在多层类系统中有一个特定的函数被调用，它在被调用时选择正确的函数。我如何告诉它选择特定类中的函数？

请让我知道需要我提供哪些其他信息才能获得正确答案，因为我不确定这是否足够或过于模糊。让我特别知道我需要提供什么，因为我也是 C# 新手。

Answer 1

我创建了我能想到的最基本的多态示例。尝试理解示例和评论，如果您有更具体的问题，我会更新帖子。

第一个代码示例包含两个类，第二个代码示例调用这些类的对象的方法来演示多态性。

public class BaseClass
{
    // This method can be "replaced" by classes which inherit this class
    public virtual void OverrideableMethod()
    {
        System.Console.WriteLine("BaseClass.OverrideableMethod()");
    }

    // This method is called when the type is of your variable is "BaseClass"
    public void Method()
    {
        Console.WriteLine("BaseClass.Method()");
    }
}

public class SpecializedClass : BaseClass
{

    // your specialized code
    // the original method from BaseClasse is not accessible anymore
    public override void OverrideableMethod()
    {
        Console.WriteLine("SpecializedClass.OverrideableMethod()");

        // call the base method if you need to
        // base.OverrideableMethod();
    }

    // this method hides the Base Classes code, but it still is accessible
    // - without the "new" keyword the compiler generates a warning
    // - try to avoid method hiding
    // - it is called when the type is of your variable is "SpecializedClass"
    public new void Method()
    {
        Console.WriteLine("SpecializedClass.Method()");
    }
}

使用以下方法测试类:

Console.WriteLine("testing base class");

BaseClass baseClass = new BaseClass();
baseClass.Method();
baseClass.OverrideableMethod();


Console.WriteLine("\n\ntesting specialized class");

SpecializedClass specializedClass = new SpecializedClass();
specializedClass.Method();
specializedClass.OverrideableMethod();


Console.WriteLine("\n\nuse specialized class as base class");

BaseClass containsSpecializedClass = specializedClass;
containsSpecializedClass.Method();
containsSpecializedClass.OverrideableMethod();