cmake_demo/library/shape.c

#include "shape.h"

double virtual_area(void *self)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

void virtual_draw(void *self)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

struct _virtual_table *virtual_new(void)
{
    struct _virtual_table *vtb = calloc(1, sizeof(struct _virtual_table));
    if (vtb == NULL)
    {
        return NULL;
    }
    vtb->area = virtual_area;
    vtb->draw = virtual_draw;
    return vtb;
}

#include "rect.h"

double shape_area(void *self)
{
    double area = 0;
    struct _shape *parent = (*(struct _rect **)self)->shape;
    area = parent->vtb.area(self);

    // struct _shape *parent = *(struct _shape **)self;
    // void * pthis = container_of(self, struct _rect, shape);
    // area = parent->vtb.area(pthis);

    // struct _rect *pthis = (struct _rect *)parent;
    // pthis->shape->vtb.draw(self, NULL);
    return area;
}

void shape_draw(void *self)
{
    struct _shape *pthis = container_of(self, struct _shape, me);
    pthis->vtb.draw(pthis);
}

PRIVATE double _shape_area(void *self)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

PRIVATE void _shape_draw(void *self)
{
    ASSERT_CALL_VIRTUAL_METHOD();
}

struct _shape *shape_new(void)
{
    struct _shape *shape = calloc(1, sizeof(struct _shape));
    if(shape == NULL)
    {
        return NULL;
    }
    shape->me = shape;

    static struct _virtual_table vtb = {
        .area = (double (*)(void *self))_shape_area, 
        .draw = (void (*)(void *self))_shape_draw
    };
    shape->vtb = vtb;
    return shape;
}

#if 0
void shape_free(struct _shape * self)
{
    if (self != NULL)
    {
        free(self);
    }
}
#endif