add original source

source/listing_2.4.cpp

@@ -0,0 +1,61 @@
+#include <thread>
+#include <string>
+
+void open_document_and_display_gui(std::string const& filename)
+{}
+
+bool done_editing()
+{
+    return true;
+}
+
+enum command_type{
+    open_new_document
+};
+
+
+struct user_command
+{
+    command_type type;
+
+    user_command():
+        type(open_new_document)
+    {}
+};
+
+user_command get_user_input()
+{
+    return user_command();
+}
+
+std::string get_filename_from_user()
+{
+    return "foo.doc";
+}
+
+void process_user_input(user_command const& cmd)
+{}
+
+void edit_document(std::string const& filename)
+{
+    open_document_and_display_gui(filename);
+    while(!done_editing())
+    {
+        user_command cmd=get_user_input();
+        if(cmd.type==open_new_document)
+        {
+            std::string const new_name=get_filename_from_user();
+            std::thread t(edit_document,new_name);
+            t.detach();
+        }
+        else
+        {
+            process_user_input(cmd);
+        }
+    }
+}
+
+int main()
+{
+    edit_document("bar.doc");
+}