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POC++: Function wrapper that behaves just like the function itself
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copied!<p>How can I write a wrapper that can wrap any function and can be called just like the function itself? </p> <p>The reason I need this: I want a Timer object that can wrap a function and behave just like the function itself, plus it logs the accumulated time of all its calls.</p> <p>The scenario would look like this:</p> <pre><code>// a function whose runtime should be logged double foo(int x) { // do something that takes some time ... } Timer timed_foo(&foo); // timed_foo is a wrapping fct obj double a = timed_foo(3); double b = timed_foo(2); double c = timed_foo(5); std::cout << "Elapsed: " << timed_foo.GetElapsedTime(); </code></pre> <p>How can I write this <code>Timer</code> class?</p> <p>I am trying something like this:</p> <pre><code>#include <tr1/functional> using std::tr1::function; template<class Function> class Timer { public: Timer(Function& fct) : fct_(fct) {} ??? operator()(???){ // call the fct_, // measure runtime and add to elapsed_time_ } long GetElapsedTime() { return elapsed_time_; } private: Function& fct_; long elapsed_time_; }; int main(int argc, char** argv){ typedef function<double(int)> MyFct; MyFct fct = &foo; Timer<MyFct> timed_foo(fct); double a = timed_foo(3); double b = timed_foo(2); double c = timed_foo(5); std::cout << "Elapsed: " << timed_foo.GetElapsedTime(); } </code></pre> <p>(BTW, I know of <code>gprof</code> and other tools for profiling runtime, but having such a <code>Timer</code> object to log the runtime of a few selected functions is more convenient for my purposes.) </p>

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