为什么我会永远需要使用C＃的嵌套类 [英] Why Would I Ever Need to Use C# Nested Classes

问题描述

我想了解有关在C＃中嵌套类。我明白，一个嵌套类是在另一个类中定义的类，有什么我不明白就是为什么我会永远需要做到这一点。

I'm trying to understand about nested classes in C#. I understand that a nested class is a class that is defined within another class, what I don't get is why I would ever need to do this.

推荐答案

这是我特别喜欢的一个模式是嵌套类的工厂模式相结合：

A pattern that I particularly like is to combine nested classes with the factory pattern:

public abstract class BankAccount
{
  private BankAccount() {} // prevent third-party subclassing.
  private sealed class SavingsAccount : BankAccount { ... }
  private sealed class ChequingAccount : BankAccount { ... }
  public static BankAccount MakeSavingAccount() { ... }
  public static BankAccount MakeChequingAccount() { ... }
}

通过嵌套像这样的课，我使它不可能对第三方创建自己的子类。我对所有在任何的BankAccount对象运行code完全控制。和我所有的子类可以通过基类的共享实施细则。

By nesting the classes like this, I make it impossible for third parties to create their own subclasses. I have complete control over all the code that runs in any bankaccount object. And all my subclasses can share implementation details via the base class.

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