diff --git a/paddle/pybind/protobuf.cc b/paddle/pybind/protobuf.cc
index 0a6020d6492f0f6db2d4d9b4769a4dcd2117391e..de3f7bb97be9787e0e9b0130a87d19529edf44f3 100644
--- a/paddle/pybind/protobuf.cc
+++ b/paddle/pybind/protobuf.cc
@@ -44,8 +44,11 @@ template <template <class...> class V, class... Ts>
 struct variant_caster<V<Ts...>> {
   using Type = V<Ts...>;
 
-  template <class T>
-  bool try_load(handle src, bool convert) {
+  template <typename T>
+  typename std::enable_if<
+      !std::is_same<T, boost::detail::variant::void_>::value,
+      bool>::type
+  try_load(handle src, bool convert) {
     auto caster = make_caster<T>();
     if (!load_success_ && caster.load(src, convert)) {
       load_success_ = true;
@@ -55,6 +58,13 @@ struct variant_caster<V<Ts...>> {
     return false;
   }
 
+  template <typename T>
+  typename std::enable_if<std::is_same<T, boost::detail::variant::void_>::value,
+                          bool>::type
+  try_load(handle src, bool convert) {
+    return false;
+  }
+
   bool load(handle src, bool convert) {
     auto unused = {false, try_load<Ts>(src, convert)...};
     (void)(unused);
@@ -210,6 +220,45 @@ public:
 
   std::string DebugString() { return this->Proto()->DebugString(); }
 
+  bool HasAttr(const std::string &name) const {
+    return attrs_.find(name) != attrs_.end();
+  }
+
+  framework::AttrType GetAttrType(const std::string &name) const {
+    auto it = attrs_.find(name);
+    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
+    return static_cast<framework::AttrType>(it->second.which() - 1);
+  }
+
+  std::vector<std::string> AttrNames() const {
+    std::vector<std::string> retv;
+    retv.reserve(attrs_.size());
+    for (auto &attr : attrs_) {
+      retv.push_back(attr.first);
+    }
+    return retv;
+  }
+
+  void SetAttr(const std::string &name, const Attribute &v) {
+    this->attrs_[name] = v;
+    need_update_ = true;
+  }
+
+  void SetBlockAttr(const std::string &name, BlockDescBind &block);
+
+  Attribute GetAttr(const std::string &name) const {
+    auto it = attrs_.find(name);
+    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
+    return it->second;
+  }
+
+  int GetBlockAttr(const std::string &name) const {
+    auto it = attrs_.find(name);
+    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
+    return boost::get<BlockDesc *>(it->second)->idx();
+  }
+
+private:
   struct SetAttrDescVisitor : public boost::static_visitor<void> {
     explicit SetAttrDescVisitor(OpDesc::Attr *attr) : attr_(attr) {}
     mutable OpDesc::Attr *attr_;
@@ -265,49 +314,13 @@ public:
     }
   }
 
-  bool HasAttr(const std::string &name) const {
-    return attrs_.find(name) != attrs_.end();
-  }
-
-  framework::AttrType GetAttrType(const std::string &name) const {
-    auto it = attrs_.find(name);
-    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
-    return static_cast<framework::AttrType>(it->second.which() - 1);
-  }
-
-  std::vector<std::string> AttrNames() const {
-    std::vector<std::string> retv;
-    retv.reserve(attrs_.size());
-    for (auto &attr : attrs_) {
-      retv.push_back(attr.first);
-    }
-    return retv;
-  }
-
-  void SetAttr(const std::string &name, const Attribute &v) {
-    this->attrs_[name] = v;
-  }
-
-  void SetBlockAttr(const std::string &name, BlockDescBind &block);
-
-  Attribute GetAttr(const std::string &name) const {
-    auto it = attrs_.find(name);
-    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
-    return it->second;
-  }
-
-  int GetBlockAttr(const std::string &name) const {
-    auto it = attrs_.find(name);
-    PADDLE_ENFORCE(it != attrs_.end(), "Attribute %s is not found", name);
-    return boost::get<BlockDesc *>(it->second)->idx();
-  }
-
-private:
   OpDesc op_desc_;
   std::unordered_map<std::string, std::vector<std::string>> inputs_;
   std::unordered_map<std::string, std::vector<std::string>> outputs_;
   std::unordered_map<std::string, Attribute> attrs_;
 
+  // need_update_ indicate there some local changes not be synchronized. If
+  // local changes should be synchronized, need_update_ should be set to true.
   bool need_update_{false};
 };
 
diff --git a/python/paddle/v2/framework/tests/test_protobuf_descs.py b/python/paddle/v2/framework/tests/test_protobuf_descs.py
index 13d819abf418f180f9e661d6c8cc03c6c70dd426..2b7ba6688a65c466d5bc656178f2991da8dfe016 100644
--- a/python/paddle/v2/framework/tests/test_protobuf_descs.py
+++ b/python/paddle/v2/framework/tests/test_protobuf_descs.py
@@ -23,6 +23,7 @@ class TestOpDesc(unittest.TestCase):
         op.set_attr("int_attr", 1)
         self.assertEqual(1, op.attr("int_attr"))
         self.assertTrue(op.has_attr("int_attr"))
+        self.assertEqual(core.AttrType.INT, op.attr_type("int_attr"))
 
         op.set_attr("float_attr", -1.32)
         self.assertAlmostEqual(-1.32, op.attr("float_attr"), delta=1e-4)
@@ -53,7 +54,6 @@ class TestOpDesc(unittest.TestCase):
 
         op.set_block_attr("block_attr", prog.block(0))
         self.assertEqual(0, op.get_block_attr("block_attr"))
-        self.assertEqual(core.AttrType.INT, op.attr_type("int_attr"))
 
 
 class TestProgramDesc(unittest.TestCase):