1 files changed, 81 insertions, 0 deletions
diff --git a/misc/examples/smartpointers/box2.c b/misc/examples/smartpointers/box2.c
new file mode 100644
index 00000000..9b782c74
--- /dev/null
+++ b/misc/examples/smartpointers/box2.c
@@ -0,0 +1,81 @@
+// example: https://doc.rust-lang.org/rust-by-example/std/box.html
+#include <stdio.h>
+
+typedef struct {
+    double x;
+    double y;
+} Point;
+
+// A Rectangle can be specified by where its top left and bottom right
+// corners are in space
+typedef struct {
+    Point top_left;
+    Point bottom_right;
+} Rectangle;
+
+#define i_key Point
+#include <stc/cbox.h> // cbox_Point
+
+#define i_key Rectangle
+#include <stc/cbox.h> // cbox_Rectangle
+
+// Box in box:
+#define i_type BoxBoxPoint
+#define i_keyboxed cbox_Point // NB: use i_keyboxed when value is a cbox or carc!
+#include <stc/cbox.h> // BoxBoxPoint
+
+Point origin(void) {
+    return c_LITERAL(Point){ .x=1.0, .y=2.0 };
+}
+
+cbox_Point boxed_origin(void) {
+    // Allocate this point on the heap, and return a pointer to it
+    return cbox_Point_make(c_LITERAL(Point){ .x=1.0, .y=2.0 });
+}
+
+
+int main(void) {
+    // Stack allocated variables
+    Point point = origin();
+    Rectangle rectangle = {
+        .top_left = origin(),
+        .bottom_right = { .x=3.0, .y=-4.0 }
+    };
+
+    // Heap allocated rectangle
+    cbox_Rectangle boxed_rectangle = cbox_Rectangle_make(c_LITERAL(Rectangle){
+        .top_left = origin(),
+        .bottom_right = { .x=3.0, .y=-4.0 }
+    });
+    // The output of functions can be boxed
+    cbox_Point boxed_point = cbox_Point_make(origin());
+
+    // Can use from(raw) and toraw instead:
+    BoxBoxPoint box_in_a_box = BoxBoxPoint_from(origin());
+
+    c_defer(
+        BoxBoxPoint_drop(&box_in_a_box),
+        cbox_Point_drop(&boxed_point),
+        cbox_Rectangle_drop(&boxed_rectangle)
+    ){
+        printf("box_in_a_box: x = %g\n", BoxBoxPoint_toraw(&box_in_a_box).x);
+
+        printf("Point occupies %d bytes on the stack\n",
+                (int)sizeof(point));
+        printf("Rectangle occupies %d bytes on the stack\n",
+                (int)sizeof(rectangle));
+
+        // box size == pointer size
+        printf("Boxed point occupies %d bytes on the stack\n",
+                (int)sizeof(boxed_point));
+        printf("Boxed rectangle occupies %d bytes on the stack\n",
+                (int)sizeof(boxed_rectangle));
+        printf("Boxed box occupies %d bytes on the stack\n",
+                (int)sizeof(box_in_a_box));
+
+        // Copy the data contained in `boxed_point` into `unboxed_point`
+        Point unboxed_point = *boxed_point.get;
+        printf("Unboxed point occupies %d bytes on the stack\n",
+                (int)sizeof(unboxed_point));
+    }
+}