C++ 类头文件组织

I have this situation in my project and solving class definition related errors crossing over several header files has become quite a headache.

推荐答案

一些通用准则:

• 将您的接口与实现配对.如果你有 foo.cxx，那么其中定义的所有内容最好在 foo.h 中声明.
• 确保每个头文件#includes所有其他必要的头文件或独立编译所需的前向声明.
• 抵制创建一切"标题的诱惑.他们总是在路上遇到麻烦.
• 将一组相关(且相互依赖)的功能放入一个文件中.Java 和其他环境鼓励每个文件一个类.使用 C++，您通常希望每个文件有一个 组 类.这取决于您的代码结构.
• 尽可能优先使用前向声明而不是 #include.这允许您打破循环头依赖关系.本质上，对于跨单独文件的循环依赖关系，您需要一个看起来像这样的文件依赖关系图:
  • A.cxx 需要 A.h 和 B.h
  • B.cxx 需要 A.h 和 B.h
  • A.h 需要 B.h
  • B.h 是独立的(并且前向声明在 A.h 中定义的类)
  • Pair up your interfaces with implementations. If you have foo.cxx, everything defined in there had better be declared in foo.h.
  • Ensure that every header file #includes all other necessary headers or forward-declarations necessary for independent compilation.
  • Resist the temptation to create an "everything" header. They're always trouble down the road.
  • Put a set of related (and interdependent) functionality into a single file. Java and other environments encourage one-class-per-file. With C++, you often want one set of classes per file. It depends on the structure of your code.
  • Prefer forward declaration over #includes whenever possible. This allows you to break the cyclic header dependencies. Essentially, for cyclical dependencies across separate files, you want a file-dependency graph that looks something like this:
    • A.cxx requires A.h and B.h
    • B.cxx requires A.h and B.h
    • A.h requires B.h
    • B.h is independent (and forward-declares classes defined in A.h)

    如果您的代码打算成为其他开发人员使用的库，则需要采取一些额外的步骤:

    If your code is intended to be a library consumed by other developers, there are some additional steps that are important to take:

    • 如有必要，请使用私有标头"的概念.也就是说，多个源文件需要的头文件，但公共接口从不需要.这可能是一个包含常见内联函数、宏或内部常量的文件.
    • 在文件系统级别将公共接口与私有实现分开.我倾向于在我的 C 或 C++ 项目中使用 include/ 和 src/ 子目录，其中 include/ 包含我所有的公共标头，并且 src/ 有我所有的来源.和私有标头.
    • If necessary, use the concept of "private headers". That is, header files that are required by several source files, but never required by the public interface. This could be a file with common inline functions, macros, or internal constants.
    • Separate your public interface from your private implementation at the filesystem level. I tend to use include/ and src/ subdirectories in my C or C++ projects, where include/ has all of my public headers, and src/ has all of my sources. and private headers.

    我建议找一本 John Lakos 的书大型 C++ 软件设计.这是一本相当厚重的书，但如果你只是浏览一下他关于物理架构的一些讨论，你会学到很多东西.

    I'd recommend finding a copy of John Lakos' book Large-Scale C++ Software Design. It's a pretty hefty book, but if you just skim through some of his discussions on physical architecture, you'll learn a lot.