diff --git a/main.c b/main.c
index 8c5f1d0..6e4ddac 100644
--- a/main.c
+++ b/main.c
@@ -1,13 +1,126 @@
 
 #include <stdint.h>
 #include <stdio.h>
+#include <stdbool.h>
 #include <stdlib.h>
 
+#define VIRTUAL
 
+struct _shape
+{
+    VIRTUAL void (*area)(struct _shape *self);
+    VIRTUAL void (*draw)(struct _shape *self);
+};
 
+void shape_area(struct _shape *self)
+{
+    printf("shape area\n");
+}
+
+void shape_draw(struct _shape *self)
+{
+    printf("shape draw\n");
+}
+
+struct _shape *shape_new(void)
+{
+    struct _shape *shape = calloc(1, sizeof(struct _shape));
+    return shape;
+}
+
+#if 0
+void shape_free(struct _shape * self)
+{
+    if (self != NULL)
+    {
+        free(self);
+    }
+}
+#endif
+
+struct _rect
+{
+    // super
+    // struct _shape shape;
+
+    // attribute
+    double width, height;
+
+    // method
+    void (*area)(struct _rect *self);
+    void (*draw)(struct _rect *self);
+};
+
+void rect_area(struct _rect *self)
+{
+    printf("rect area = %0.2f\n", self->width * self->height);
+}
+
+void rect_draw(struct _rect *self)
+{
+    printf("rect draw\n");
+}
+
+struct _rect *rect_new(double width, double height)
+{
+    struct _rect *rect = calloc(1, sizeof(struct _rect));
+    if (rect == NULL)
+    {
+        return NULL;
+    }
+    rect->width = width;
+    rect->height = height;
+
+    rect->area = rect_area;
+    rect->draw = rect_draw;
+    return rect;
+}
+
+struct _circle
+{
+    // super
+    // struct _shape shape;
+
+    // attribute
+    double radius;
+
+    // method
+    void (*area)(struct _circle *self);
+    void (*draw)(struct _circle *self);
+};
+
+void circle_area(struct _circle *self)
+{
+    printf("circle area = %0.2f\n", 3.14 * self->radius * self->radius);
+}
+void circle_draw(struct _circle *self)
+{
+    printf("circle draw\n");
+}
+
+struct _circle *circle_new(double radius)
+{
+    struct _circle *circle = calloc(1, sizeof(struct _circle));
+    if (circle == NULL)
+    {
+        return NULL;
+    }
+    circle->radius = radius;
+
+    circle->area = circle_area;
+    circle->draw = circle_draw;
+    return circle;
+}
 
 int main(int argc, char *argv[])
 {
+    struct _rect *rect = rect_new(4, 5);
+    rect->area(rect);
+    rect->draw(rect);
+
+    struct _circle *circle = circle_new(3);
+    circle->area(circle);
+    circle->draw(circle);
 
     return 0;
 }
diff --git a/mk.bat b/mk.bat
index 6c46bd1..aedfdac 100644
--- a/mk.bat
+++ b/mk.bat
@@ -9,3 +9,5 @@ make -C build test
 
 @REM cpack -C ./build/CPackConfig.cmake
 @REM cpack -C ./build/CPackSourceConfig.cmake
+
+"build/release/bin/demo.exe"