linux-kernel - 为什么结构化类型通过结构标记而不是类型名来引用？

Question

在Linux内核中，结构化类型的定义如下:

typedef struct _TAG_ { ... };

然后在这样的例程中使用:

struct _TAG_ structured_entity;   
struct _TAG_ *pointer_to_structured_entity;
void function(struct _TAG_ *arg, ...);

为什么不这样:

typedef struct _TAG_ { ... } _typename_; 

然后:

_typename_ structured_entity;   
_typename_ *pointer_to_structured_entity;
void function(_typename_ *arg, ...);

这样做的技术必要性是什么？或者这只是传统/风格/魔法？

Answer 1

Linux kernel coding style - 在 kernel.org 和内核附带的文档目录中 - 不鼓励对结构使用 typedef:

Chapter 5: Typedefs

Please don't use things like "vps_t".

It's a _mistake_ to use typedef for structures and pointers. When you see a

    vps_t a;

in the source, what does it mean?

In contrast, if it says

    struct virtual_container *a;

you can actually tell what "a" is.

该文档继续列出了作者认为 typedef 有用的情况 - 例如只能使用访问器函数访问的不透明对象 - 最后是:

In general, a pointer, or a struct that has elements that can reasonably
be directly accessed should _never_ be a typedef.