diff --git a/binding/lua53/protobuf.lua b/binding/lua53/protobuf.lua
index 40ca42b..293df3e 100644
--- a/binding/lua53/protobuf.lua
+++ b/binding/lua53/protobuf.lua
@@ -215,7 +215,9 @@ local function encode_message(CObj, message_type, t)
 	local type = encode_type_cache[message_type]
 	for k,v in pairs(t) do
 		local func = type[k]
-		func(CObj, k , v)
+		if func then
+			func(CObj, k , v)
+		end
 	end
 end
 
@@ -305,8 +307,11 @@ local _encode_type_meta = {}
 
 function _encode_type_meta:__index(key)
 	local t, msg = c._env_type(P, self._CType, key)
-	local func = assert(_writer[t],key)(msg)
-	self[key] = func
+	local func = _writer[t]
+	if func then
+		func = func(msg)
+		self[key] = func
+	end
 	return func
 end
 
diff --git a/pbc.h b/pbc.h
index 26312af..2f36c35 100644
--- a/pbc.h
+++ b/pbc.h
@@ -71,7 +71,7 @@ const char * pbc_rmessage_string(struct pbc_rmessage * , const char *key , int i
 struct pbc_rmessage * pbc_rmessage_message(struct pbc_rmessage *, const char *key, int index);
 int pbc_rmessage_size(struct pbc_rmessage *, const char *key);
 int pbc_rmessage_next(struct pbc_rmessage *, const char **key);
-
+// 新建pbc_wmessage
 struct pbc_wmessage * pbc_wmessage_new(struct pbc_env * env, const char *type_name);
 void pbc_wmessage_delete(struct pbc_wmessage *);
 
diff --git a/src/alloc.c b/src/alloc.c
index 96590ed..8b5448d 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -2,7 +2,7 @@
 #include <stdio.h>
 
 static int _g = 0;
-
+// 分配内存，并记录到_g
 void * _pbcM_malloc(size_t sz) {
 	++ _g;
 	return malloc(sz);
@@ -60,11 +60,11 @@ _pbcH_delete(struct heap *h) {
 	}
 	_pbcM_free(h);
 }
-
+// 创建一个堆；h：全局堆， size：堆大小
 void* 
 _pbcH_alloc(struct heap *h, int size) {
 	size = (size + 3) & ~3;
-	if (h->size - h->used < size) {
+	if (h->size - h->used < size) { // 内存不够
 		struct heap_page * p;
 		if (size < h->size) {
 			p = (struct heap_page *)_pbcM_malloc(sizeof(struct heap_page) + h->size);
diff --git a/src/wmessage.c b/src/wmessage.c
index 8c10165..ca1d758 100644
--- a/src/wmessage.c
+++ b/src/wmessage.c
@@ -14,15 +14,15 @@
 #endif
 
 #define WMESSAGE_SIZE 64
-
+// pbc编码结构体
 struct pbc_wmessage {
-	struct _message *type;
-	uint8_t * buffer;
-	uint8_t * ptr;
-	uint8_t * endptr;
-	pbc_array sub;
-	struct map_sp *packed;
-	struct heap * heap;
+	struct _message *type; // 
+	uint8_t * buffer;      //
+	uint8_t * ptr;         //
+	uint8_t * endptr;      //
+	pbc_array sub;         //
+	struct map_sp *packed; //
+	struct heap * heap;    //
 };
 
 struct _packed {
@@ -30,7 +30,7 @@ struct _packed {
 	int ptype;
 	pbc_array data;
 };
-
+// 新建pbc_wmessage
 static struct pbc_wmessage *
 _wmessage_new(struct heap *h, struct _message *msg) {
 	struct pbc_wmessage * m = (struct pbc_wmessage *)_pbcH_alloc(h, sizeof(*m));