Question

在Linux内核中，结构化类型的定义如下：

typedef struct _TAG_ { ... };

然后用于这样的例程：

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/魔术？

Answer 1

在kernel.org和内核附带的Documentation目录中的Linux kernel coding style - 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.

该文档继续列出作者认为typedef很有用的情况 - 例如只能使用访问器函数访问的不透明对象 - 以下结尾：

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

为什么结构化类型是由struct标签而不是typename引用的？

1 个答案: