add original source

source/listing_4.8.cpp

@@ -0,0 +1,9 @@
+template<>
+class packaged_task<std::string(std::vector<char>*,int)>
+{
+public:
+    template<typename Callable>
+    explicit packaged_task(Callable&& f);
+    std::future<std::string> get_future();
+    void operator()(std::vector<char>*,int);
+};