A trivial change on demos.

examples/echo_client/echo_client.cpp

@@ -30,7 +30,7 @@
 #define ASCS_MSG_BUFFER_SIZE 1000000
 #define ASCS_MAX_SEND_BUF (10 * ASCS_MSG_BUFFER_SIZE)
 #define ASCS_MAX_RECV_BUF (10 * ASCS_MSG_BUFFER_SIZE)
-#define ASCS_DEFAULT_UNPACKER flexible_unpacker<std::string>
+#define ASCS_DEFAULT_UNPACKER flexible_unpacker<>
 //this unpacker only pre-allocated a buffer of 4000 bytes, but it can parse messages up to ST_ASIO_MSG_BUFFER_SIZE (here is 1000000) bytes,
 //it works as the default unpacker for messages <= 4000, otherwise, it works as non_copy_unpacker
 #elif 1 == PACKER_UNPACKER_TYPE

examples/echo_server/echo_server.cpp

@@ -30,7 +30,7 @@
 #define ASCS_MSG_BUFFER_SIZE 1000000
 #define ASCS_MAX_SEND_BUF (10 * ASCS_MSG_BUFFER_SIZE)
 #define ASCS_MAX_RECV_BUF (10 * ASCS_MSG_BUFFER_SIZE)
-#define ASCS_DEFAULT_UNPACKER flexible_unpacker<>
+#define ASCS_DEFAULT_UNPACKER flexible_unpacker<std::string>
 //this unpacker only pre-allocated a buffer of 4000 bytes, but it can parse messages up to ST_ASIO_MSG_BUFFER_SIZE (here is 1000000) bytes,
 //it works as the default unpacker for messages <= 4000, otherwise, it works as non_copy_unpacker
 #elif 1 == PACKER_UNPACKER_TYPE