构造函数注入-我们是否也注入工厂？ [英] Constructor Injection - Do we inject factories as well?

问题描述

听了清洁代码讨论之后，我了解到我们应该使用工厂来组成对象。因此，例如，如果房屋具有门和门有一个 DoorKnob ，在 HouseFactory 中，我们创建了一个新的 DoorKnob 并将其传递给 Door 的构造函数，然后将该新的 Door 对象传递给 House 。

After listening to the Clean Code Talks, I came to understand that we should use factories to compose objects. So, for example, if a House has a Door and a Door has a DoorKnob, in HouseFactory we create a new DoorKnob and pass it to the constructor of Door, and then pass that new Door object to the constructor of House.

但是使用 House （假设类名称为 ABC ）？这取决于 HouseFactory ，对吧？那么我们是否在 ABC 的构造函数中传递 HouseFactory ？

But what about the class that uses the House (say the class name is ABC)? It will depend on the HouseFactory, right? So do we pass the HouseFactory in the constructor of ABC? Won't we have to pass a whole lot of factories in the constructor that way?

推荐答案

停留在Door and DoorKnob示例中，我们是否需要在构造函数中传递大量工厂？ ，您不需要注入工厂-您可以注入DooKnob本身：

Staying with the Door and DoorKnob example, you don't inject a factory - you inject the DooKnob itself:

public class Door
{
    private readonly DoorKnob doorKnob;

    public Door(DoorKnob doorKnob)
    {
        if (doorKnob == null)
            throw new ArgumentNullException("doorKnob");

        this.doorKnob = doorKnob;
    }
}

在此级别上看不到任何工厂。

No factories are in sight in this level.

另一方面，房屋取决于门，而不取决于门把手：

House, on the other hand, depends on Door, but not on DoorKnob:

public class House
{
    private readonly Door door;

    public House(Door door)
    {
        if (door == null)
            throw new ArgumentNullException("door");

        this.door = door;
    }
}

这将使选项保持打开状态，直到最后您必须组成应用程序的组成根：

This keeps options open until at last you have to compose everything in the application's Composition Root:

var house = new House(new Door(new DoorKnob()));

您可以使用DI容器在此级别进行撰写，但不必这样做。没有工厂参与。

You can use a DI Container to compose at this level, but you don't have to. No factories are involved.

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