Re: Is c++ only better c ?

"James Kanze" <james.kanze@gmail.com> wrote in message
news:ded8588f-baa2-4229-a17e-b658a95105fc@34g2000hsh.googlegroups.com...
On Oct 24, 11:55 am, Maxim Yegorushkin <maxim.yegorush...@gmail.com>
wrote:


[...]

You can get "fairly clean" abstract interfaces in C; something as simple as;
quick code scribbling - may have typo:

IShape.h
--------------------------------------------
struct IShape_VTable {
  void (*IObject_Destroy) (void*);
  void (*IShape_Draw) (void*);
  /* ect... */
};

struct IShape {
  struct IShape_VTable* VTable;
};

#define IObject_Destroy(Self) ( \
  (Self)->VTable->IObject_Destroy((Self)) \
)

#define IShape_Draw(self) ( \
  (Self)->VTable->IShape_Draw((Self)) \
)

That all the infrastructure. Now to create actual shapes...

Circle.h
--------------------------------------------
extern struct IShape*
Circle_Create(
 /* ... */
);

Circle.c
--------------------------------------------
#include "Circle.h"
#include <stdlib.h>

static void Circle_IObject_Destroy(void*);
static void Circle_IShape_Draw(void*);

static struct IShape_VTable Circle_VTable = {
  Circle_IObject_Destroy,
  Circle_IShape_Draw
};

struct Circle {
  struct IShape IShape;
  /* ... */
};

struct IShape*
Circle_Create(
 /* ... */
) {
  struct Circle* Self = malloc(*Self);
  if (Self) {
    Self->IShape.VTable = &Circle_VTable;
    return &Self->IShape;
  }
  return NULL;
}

void
Circle_IObject_Destroy(
 void* IObject
) {
  free(IObject);
}

void
Circle_IShape_Draw(
 void* IShape
) {
  struct Circle* const Self = IShape;
  /* ... */
}

Now, finally we can use the Circle via. the abstract interfaces IShape and
IObject:

main.c
--------------------------------------
#include "Circle.h"

int main(void) {
  struct IShape* Shape = Circle_Create(/* ... */);
  IShape_Draw(Shape);
  IObject_Destroy(Shape);
  return 0;
}

There... simple!

;^D