diff --git a/assignments/PA5/cgen.cc b/assignments/PA5/cgen.cc
index e7a0b4a..cf52926 100644
--- a/assignments/PA5/cgen.cc
+++ b/assignments/PA5/cgen.cc
@@ -601,7 +601,39 @@ void CgenClassTable::code_dispatchTable() {
   }
 }
 
-void CgenClassTable::code_prototypeObject() {}
+void CgenClassTable::code_prototypeObject() {
+  auto int_default = inttable.lookup_string("0");
+  auto str_default = stringtable.lookup_string("");
+  auto bool_default = &falsebool;
+
+  for (auto node : nodes) {
+    str << WORD << "-1\n";                          // GC tag
+    str << node->name << PROTOBJ_SUFFIX << LABEL;   // proto obj label
+    str << WORD << node->get_class_tag() << endl;   // class tag
+    str << WORD << node->get_object_size() << endl; // object size
+    str << WORD << node->get_name() << DISPTAB_SUFFIX << endl; // dispatch ptr
+    for (auto attr : *node->get_attributes()) {
+      if (attr->type_decl == Int) {
+        str << WORD;
+        int_default->code_ref(str);
+        str << endl;
+      } else if (attr->type_decl == Bool) {
+        str << WORD;
+        bool_default->code_ref(str);
+        str << endl;
+      } else if (attr->type_decl == Str) {
+        str << WORD;
+        str_default->code_ref(str);
+        str << endl;
+      } else {
+        // for other types(including _prim_slot type), set to void(null pointer)
+        str << WORD;
+        str << 0;
+        str << endl;
+      }
+    }
+  }
+}
 
 CgenClassTable::CgenClassTable(Classes classes, ostream &s) : str(s) {
   enterscope();
@@ -903,11 +935,10 @@ void CgenClassTable::code() {
   nodes[0]->traverse_generate_object();
   // nodes[0] is the Object class
   code_dispatchTable();
-  //                 Add your code to emit
-  //                   - prototype objects
-  //                   - class_nameTab
-  //                   - dispatch tables
-  //
+
+  if (cgen_debug)
+    cout << "coding prototype objects" << endl;
+  code_prototypeObject();
 
   if (cgen_debug)
     cout << "coding global text" << endl;
diff --git a/assignments/PA5/example.cl b/assignments/PA5/example.cl
index 163f1a9..020fb7b 100644
--- a/assignments/PA5/example.cl
+++ b/assignments/PA5/example.cl
@@ -21,6 +21,7 @@ class B inherits A {
 
 class C inherits A {
   attr_C_1 : String <- "This is C\n";
+  attr_C_2 : SELF_TYPE;
   method_common(x1: Int) : SELF_TYPE {
     self
   };