Prefix / namespace suggestion

[rboati]

I would suggest to change the actual prefix system with something more flexible.
I really like the one header idea but current implementation doesn't allow to choose a comfortable prefix and avoid collisions at the same time.
In contrast, for example, consider the following main.c:

#include <stdio.h>

#define MYLIB_H_IMPLEMENTATION
#define MYLIB_H_PREFIX a_
// For no prefix just #define MYLIB_H_PREFIX
// For default prefix no action is required
#include "mylib.h"


#define ANOTHERLIB_H_IMPLEMENTATION
#define ANOTHERLIB_H_NAME(x) x ## _from_anotherlib
#include "anotherlib.h"


int main(int argc, char *argv[]) {
	a_hello();
	hello_from_anotherlib();
	return 0;
}

Both headers export a hello function.
For the first #include there is a simpler version in which the user choose the prefix it would like to use for the module symbols.
For the second #include there is a slightly more advanced version in which the user defines the naming macro to use for the module symbols.
The headers could be implemented as follows:
mylib.h

#ifndef MYLIB_H_GUARD
#define MYLIB_H_GUARD

#ifndef MYLIB_H_PREFIX
#define MYLIB_H_PREFIX mylib_
#endif // MYLIB_H_PREFIX

#ifndef MYLIB_H_NAME
#define MYLIB_H_CONCAT_HELPER(x, y) x ## y
#define MYLIB_H_CONCAT(x, y) MYLIB_H_CONCAT_HELPER(x, y)
#define MYLIB_H_NAME(x) MYLIB_H_CONCAT(MYLIB_H_PREFIX, x)
#endif // MYLIB_H_NAME

#define mylib_hello MYLIB_H_NAME(hello)

void mylib_hello();

#ifdef MYLIB_H_IMPLEMENTATION
#include <stdio.h>

void mylib_hello() {
	printf("Hello, World from mylib!\n");
}

#endif // MYLIB_H_IMPLEMENTATION

// cleanup macros
#undef mylib_hello

#undef MYLIB_H_CONCAT_HELPER
#undef MYLIB_H_CONCAT
#undef MYLIB_H_NAME
#undef MYLIB_H_IMPLEMENTATION

#endif // MYLIB_H_GUARD

You get the idea, anyway:
anotherlib.h

#ifndef ANOTHERLIB_H_GUARD
#define ANOTHERLIB_H_GUARD

#ifndef ANOTHERLIB_H_NAME
#define ANOTHERLIB_H_NAME(x) anotherlib_ ## x
#endif // ANOTHERLIB_H_NAME

#define anotherlib_hello ANOTHERLIB_H_NAME(hello)

void anotherlib_hello();

#ifdef ANOTHERLIB_H_IMPLEMENTATION
#include <stdio.h>

void anotherlib_hello() {
	printf("Hello, World from anotherlib!\n");
}

#endif // ANOTHERLIB_H_IMPLEMENTATION

// cleanup macros
#undef anotherlib_hello

#undef ANOTHERLIB_H_NAME
#undef ANOTHERLIB_H_IMPLEMENTATION

#endif // ANOTHERLIB_H_GUARD

I already tried this implementation and it works as intended.

[rboati]

Unfortunately it doesn't work for macros as they cannot have a dynamic name and the user needs to define aliases manually