Added a class to hold ruby objects.

include/bindings/ruby.h

@@ -88,6 +88,35 @@ struct Block {
   }
 };
 
+struct RubyObject {
+  mrb_value val;
+
+  RubyObject(mrb_value val) : val(val) {
+    mrb_gc_register(mrb, val);
+  }
+
+  RubyObject() : val(mrb_nil_value()) {}
+
+  ~RubyObject() {
+    if (!mrb_nil_p(val))
+      mrb_gc_unregister(mrb, val);
+  }
+
+  void set_proc(mrb_value new_proc) {
+    if (!mrb_nil_p(val))
+      mrb_gc_unregister(mrb, val);
+    val = new_proc;
+    mrb_gc_register(mrb, val);
+  }
+
+  RubyObject(const RubyObject &) = delete;
+  RubyObject &operator=(const RubyObject &) = delete;
+
+  mrb_value get() {
+    return val;
+  }
+};
+
 inline void run_string(const char *code, size_t length) {
   int ai = mrb_gc_arena_save(mrb);
   mrb_load_nstring(mrb, code, length);