似乎不能取消该参数，因为不借助子类的结构体信息，是无法通过父类获取到子类结构体起始点的

library/common.h

@@ -7,7 +7,6 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <assert.h>
-#include <stdarg.h>
 
 // [warring] offsetof is redefined in stddef.h
 // 

library/rect.c

@@ -4,7 +4,8 @@
 double rect_area(void *self)
 {
     double area = 0;
-    struct _rect *pthis = container_of(self, struct _rect, me);
+    struct _rect *pthis = *(struct _rect **)self;
+    // struct _rect *pthis = container_of(self, struct _rect, me);
     area = pthis->shape->vtb.area(pthis);
     return area;
 }

library/shape.c

@@ -23,13 +23,20 @@ struct _virtual_table *virtual_new(void)
     return vtb;
 }
 
-
+#include "rect.h"
 
 double shape_area(void *self)
 {
     double area = 0;
-    struct _shape *pthis = container_of(self, struct _shape, me);
+    struct _shape *parent = (*(struct _rect **)self)->shape;
-    area = pthis->vtb.area(pthis);
+    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;
 }
 

src/main.c

@@ -7,7 +7,7 @@
 int main(int argc, char *argv[])
 {
     struct _rect *rect = rect_new(4, 5);
-    rect_area(rect);
+    rect_area(&rect);
     rect_draw(rect);
 
     struct _circle *circle = circle_new(2);
@@ -15,7 +15,9 @@ int main(int argc, char *argv[])
     circle_draw(circle);
 
     printf("----- rect & circle -----\n");
-    shape_area(rect->shape);
+    // shape_area(rect);
+
+    shape_area(&rect);
     shape_draw(rect->shape);
 
     shape_area(circle->shape);