Question

To make a struct’s members “private” to the outside I know that I can do this.

In the .h file

typedef struct Obj Obj;

In the .c file you then

struct Obj {
int a;
int b;
}

This will keep the knowledge of the existense of a and b from beeing known. But all the “member” functions in the .c file will now about them and can opperate on then.
But what I wonder about now is that if you can make PART of the struct “private”. Say that I want to keep those a and b variables “private” but then I want to have some function pointers that I want to remain public. Is this possible?
I know that if I try to declare these in the struct in the .h file I would get a duplicate declaration error on the struct.

Answer 1

Could this (not tested or even compiled) work for you?

in the file “everybody_includes_me.h”:

typedef public_struct {
  func1_ptr;
  func2_ptr;
} PUBLIC_STRUCT;

extern PUBLIC_STRUCT func_pointers;

and in the file "totally_public.c":

PUBLIC_STRUCT func_pointers;

then in the file "all_private.c":

struct Obj {
  PUBLIC_STRUCT *func_pointers;
  int a;
  int b;
}