依赖性反转原理是什么，为什么重要呢? [英] What is the dependency inversion principle and why is it important?

问题描述

依赖反转的原理是什么，为什么如此重要?

What is the dependency inversion principle and why is it important?

推荐答案

签出该文档:它基本上说:

• 高级模块不应依赖于低级模块.两者都应依赖抽象.
• 抽象永远不要依赖细节.细节应取决于抽象.

简而言之，为何如此重要:变更是有风险的，并且通过依赖概念而不是实施来减少呼叫站点的变更需求.

As to why it is important, in short: changes are risky, and by depending on a concept instead of on an implementation, you reduce the need for change at call sites.

有效地，DIP减少了不同代码段之间的耦合.这个想法是，尽管有很多实现日志工具的方法，但是您使用它的方法应该在时间上相对稳定.如果您可以提取一个表示日志记录概念的接口，则该接口在时间上应比其实现稳定得多，并且呼叫站点受维护或扩展该日志记录机制时所做的更改的影响要小得多.

Effectively, the DIP reduces coupling between different pieces of code. The idea is that although there are many ways of implementing, say, a logging facility, the way you would use it should be relatively stable in time. If you can extract an interface that represents the concept of logging, this interface should be much more stable in time than its implementation, and call sites should be much less affected by changes you could make while maintaining or extending that logging mechanism.

通过还使实现依赖于接口，您可以在运行时选择哪种实现更适合您的特定环境.视情况而定，这也可能很有趣.

By also making the implementation depend on an interface, you get the possibility to choose at run-time which implementation is better suited for your particular environment. Depending on the cases, this may be interesting too.

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