dongxi1680 2016-08-30 10:31
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当我们在框架上下文中谈论它时,单例模式是否仍然不好?

Using the singleton pattern is usually a code smell.

However, it seems that using "singletons" in a framework such as Laravel is a popular solution to a lot of problems.

It's also worth noting that singletons in Laravel aren't really the same thing as a singleton class in the following sense:

  • The class being used as a singleton is unaware of this, there are no static methods in there, nor is there anything that would prevent you from creating a new instance of that class manually.
  • When using Laravel singletons, the container keeps track of the objects you want to use as singleton and hands these to you upon request.

Am I correct in my understanding that what is called a singleton in Laravel isn't in fact a singleton, but an implementation inspired by the singleton pattern, and therefore isn't as much as a bad practice as a real singleton because it gets rid of some of the downsides (harder to test, global state...)?

This question is loosely related to this question about design patterns in PHP but it appeared appropriate to me to create a separate question.

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  • doujiong3146 2016-09-01 18:19
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    Yes, it is still bad. It is still an anti-pattern.

    The fact, that you see many people resorting to this, simply indicate the flaws in any given system. It applies to applications, frameworks and libraries.

    And saying that "our singletons are different" is just wrong. And, if you were writing proper unit tests, you would be testing your code in isolation, without having to initialize various parts of a framework.

    P.S.
    You seem to have wrong opinion of what "code smell" is. Code smell is when you have variables named $a1, $bzzzz, code smell is when your functions have 8 parameters. Anit-pattern is not a code smell. It is a mistake in architecture.

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