在C ++中使用命名空间代替静态类？ [英] Using a namespace in place of a static class in C++?

问题描述

使用命名空间作为静态类是好还是好。例如：

Is it good or okay practice to use a namespace as a static class. For example:

namespace MyStaticFunctions {
    void doSomething();
}

相对：

class MyStaticFunctions {
    static void doSomething();
}

- 编辑 -

我发现很难选择一个答案，因为这么多人是有帮助的。我投票了所有人的答案。感谢一堆！

I found it difficult to pick an answer as so many people were helpful. I've voted up everyones answers. Thanks a bunch!

推荐答案

在C ++中没有一个静态类，所以从C ++的角度来看， 're不使用它作为一个静态类，你使用它作为命名空间。这是肯定接受的做法，使用命名空间将函数组合在一起。

There's no such thing as a "static class" in C++, so from a C++ point of view you're not using it "as a static class", you're using it "as a namespace". It's certainly accepted practice to use namespaces to group functions together.

这取决于你，但是，你想要的组是多大。 C ++库在整个公共接口上使用单个命名空间并不奇怪。对于习惯于（比如说）Java的人来说，这可能是一个惊喜，其中类通常用于将更少数量的静态方法组合在一起。因为C ++在这里是第一个，你可以说Java正在使用类作为命名空间。

It's up to you, though, how big you want the groups to be. It's not unusual for C++ libraries to use a single namespace for the whole public interface. That might come as a surprise to someone who is used to (say) Java, where classes are often used to group together smaller numbers of static methods. Since C++ was here first, you could say that Java is using classes as namespaces.

因此，在C ++中，你不会看到类似 java.util.Collections 或 java.lang.Math ，充满了静态成员。

So, in C++ you don't tend to see classes similar to java.util.Collections or java.lang.Math, full of static members. If you want groups of functions like that in C++, use namespaces.

异常（C ++中并不总是有一个特例）？traits类型如 std :: numeric_limits< T> ，其中模板参数使得类做某些命名空间不能做的事情。您可以定义一个命名空间 numeric_limits 包含函数模板 max< T>（）， T>（）等，但它不是那么好。首先，它对事情稍有不同，类型 T 出现降低层次结构。其次它不做一个traits类型做的一切，因为没有一个对象模板，让你定义一个值 numeric_limits :: digits< T> 。

The exception (isn't there always a special case in C++?) is traits types like std::numeric_limits<T>, where the template parameter makes the class do something that a namespace can't do. You could define a namespace numeric_limits containing function templates max<T>(), min<T>() etc, but it's not as good. Firstly, it groups things slightly differently, the type T appears "lower down the hierarchy". Secondly it doesn't do everything that a traits type does, because there's no such thing as an "object template" that would let you define a value numeric_limits::digits<T>.

我不知道C＃足以评论静态类的实际用法，但AFAIK它只是一个类限制没有非静态成员，因此它类似于那些Java类。

I don't know C# well enough to comment on the practical uses of static classes there, but AFAIK it's just a class restricted to having no non-static members, so it's analogous to those Java classes.

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