sutton036

In a recently-posted video , Herb Sutter (a prominent C++ expert) describes his favorite C++ 10-liner as “a thread-safe reference-counted object cache”: shared_ptr<widget> get_widget(int id) {   static map<int, weak_ptr<widget>> cache;   static mutex m;   lock_guard<mutex> hold(m);   auto sp = cache[id].lock();   if (!sp) cache[id] = sp = load_widget(id);   return sp; } This example is very interesting. Firstly, it manages to pull in reference counting, weak references and a mutex which are all very rare in modern programming. Secondly, it contains a memory leak that is difficult to fix in C++ because APIs are burdened with memory management details and this API is incapable of expressing deterministic cleanup because there is no facility for a widget's destructor to remove its entry in the map. Finally, the correct name for this data structure is a concurrent weak dictionary , specifically one with weak values. You'll find corre...

According to Herb Sutter, C++ (and C and Fortran) are unmatched for performance per dollar and, therefore, he believes C++ will once again top the programming language charts as mobile devices make power consumption (which he equates with performance) a high priority again: Herb said this in his recent lecture  Why C++?  and other Microsoft employees from the Visual C++ team have called this prophecy the  "C++ Renaissance" . Similar statements about the superior performance of C++ were commonplace over 15 years ago when Java was new and unproven but we now know they were almost entirely wrong. The world migrated from native to managed languages over 10 years ago and never looked back because their performance is more than adequate. Furthermore, the implementations of managed languages have improved substantially since then and even toy benchmarks now show them competing with or even beating native code. Furthermore, the difficulty of optimizing large code bases means that...