How can one emulate the C++ namespace feature in a C code?

Question

I'm developing a software which is in C++ but that communicates with a C app through a shared header file containing the communication protocol. Since C is "more basic" than C++, I always need to write the header in C code (so C++ also gets it); otherwise it wouldn't work for the second app.

The problem is that I need to use a scope-quilifier such as the C++ namespaces - which don't exist in C.

What are all the options to emulate the namespace feature in C?

The only possibility I have seen so far is the one shown in this SO question, but unfortunately the answer is not clear enough and I would certainly like to know if there are other options. I also tried to use structs to do the job, without success (at least considering a struct with an enumerator).

Answer 1

You can hide all of your exported functions from being exported from the module with static at the definition level, so that no names are placed in the global space, and instead put them in a struct that is the only thing provided by the module.

E.g. foo.h:

struct ns_t {
    int (*a)(int, int);
    void (*b)(float, float);
};
extern struct ns_t ns;

foo.c:

#include "foo.h"

static int a(int x, int y) {
    ...
}

static void b(float x, float y) {
    ...
}

struct ns_t ns = { .a = a, .b = b };

bar.c:

#include "foo.h"
....
ns.b(4.5, 6.8);
....