ruin

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
/* base.h */
 
struct base;
struct base_vtable {
    const char *type;
    int (*foo) (struct base *);
    int (*bar) (struct base *, int val);
    void (*release) (struct base *);
};
 
struct base {
    struct base_vtable *vptr;
};
 
int base_foo (struct base *b) {
    return b->vptr->foo (b);
}
 
int base_bar (struct base *b, int val) {
    return b->vptr->bar (b, val);
}
 
void base_release (struct base *b) {
    b->vptr->release (b);
}
 
void base_init (struct base *b) {
    b->vptr->type = "BASE";
    b->vptr->foo = &base_foo;
    b->vptr->bar = &base_bar;
}
 
/* derive.h */
struct derive {
    struct base super;
    int m;
};
 
void *derive_init();
int derive_foo (struct derive *d);
int derive_bar (struct derive *d, int val);
void derive_release (struct derive *d);
 
/* derive.c */
 
int derive_foo (struct derive *d) {
    printf ("derive_foo: %d\n", d->m);
}
 
int derive_bar (struct derive *d, int val) {
    printf ("derive_bar: %d\n", val);
}
 
void derive_release (struct derive *d) {
    puts ("derive_release");
    free(d);
}
 
struct base_vtable derive_vtable = {
    .type = "DERIVE",
    .foo = (void*)derive_foo,
    .bar = (void*)derive_bar,
    .release = (void*)derive_release,
};
 
void *derive_init () {
    struct derive* d = (struct derive*)malloc (sizeof (struct derive));
    d->super.vptr = &derive_vtable;
    d->m = 4321;
    puts("derive_init");
    return d;
}
 
int main (int argc, char *argv[]) {
    struct base* b = derive_init ();
    base_foo(b);    
    base_bar(b, 1234);  
/*  printf("%s\n", b->vptr->type); */
    base_release(b);
    return 0;
}