为什么抽象工厂使用抽象类而不是接口？ [英] Why does Abstract Factory use abstract class instead of interface?

问题描述

我学习设计模式，并在书中的第一个例子是关于抽象工厂。
我已经建立了演习VS和所有看起来不错，但有一个问题，我想知道。

I am learning about design patterns and the first example in the book is about Abstract Factory. I have built the exercise in VS and all looks good, but there is one question that I wonder about.

在书中的工厂类等来实现这样的：

In the book the factory class is implemented like this:

public abstract class AbstractVehicleFactory
{
    public abstract IBody CreateBody();
    public abstract IChassis CreateChassis();
    public abstract IGlassware CreateGlassware();
}

完成我已注意到，上述类可以用此来代替的练习后代码：

After completing the exercise I have noted that the above class can be replaced with this code:

public interface IAbstractVehicleFactory
{
      IBody CreateBody();
      IChassis CreateChassis();
      IGlassware CreateGlassware();
}

当然这两个例子的功能完全一样，但我不知道是什么原因用一个抽象类，而不是一个接口？

Of course both examples function exactly the same, but I wonder what is the reason for using an abstract class and not an interface?

推荐答案

这是抽象类能，谨慎，可以在一个非中断扩展方式; 。一个接口的所有更改重大更改

An abstract class can, with care, be extended in a non-breaking manner; all changes to an interface are breaking changes.

更新：结果
相反，接口可以是<强>在或退出类型参数和抽象类不能。有时，一个或另一个更适合于给定的设计，有时则是胜负难料。

Update:
In contrast, an interface can be an in or out type-parameter and an abstract class cannot. Sometimes one or the other is more appropriate for a given design, and sometimes it is a toss-up.

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