A good example for such a loop is an animation. In message oriented programming (and this is was libcppa is about), the most idiomatic way to implement such a loop is to send a message to yourself that is delayed by a predefined amount of time. If you receive that message, you do the next animation step and send another delayed message to yourself, and so on, until the animation is done.
Today's example is a terminal-animation with a dancing Kirby. Have fun!
#include <chrono> #include <iostream> #include <algorithm> #include "cppa/cppa.hpp" using std::cout; using std::endl; using namespace cppa; // ASCII art figures constexpr const char* figures[] = { "<(^.^<)", "<(^.^)>", "(>^.^)>" }; // array of {figure, offset} pairs constexpr size_t animation_steps[][2] = { {1, 7}, {0, 7}, {0, 6}, {0, 5}, {1, 5}, {2, 5}, {2, 6}, {2, 7}, {2, 8}, {2, 9}, {2, 10}, {1, 10}, {0, 10}, {0, 9}, {1, 9}, {2, 10}, {2, 11}, {2, 12}, {2, 13}, {1, 13}, {0, 13}, {0, 12}, {0, 11}, {0, 10}, {0, 9}, {0, 8}, {0, 7}, {1, 7} }; constexpr size_t animation_width = 20; // "draws" an animation step: {offset_whitespaces}{figure}{padding} void draw_kirby(size_t const (&animation)[2]) { cout.width(animation_width); cout << '\r'; std::fill_n(std::ostream_iterator<char>{cout}, animation[1], ' '); cout << figures[animation[0]]; cout.fill(' '); cout.flush(); } void dancing_kirby() { // let's get it started send(self, atom("Step")); // iterate over animation_steps auto i = std::begin(animation_steps); receive_for(i, std::end(animation_steps)) ( on<atom("Step")>() >> [&]() { draw_kirby(*i); // animate next step in 150ms delayed_send(self, std::chrono::milliseconds(150), atom("Step")); } ); } int main() { cout << endl; dancing_kirby(); cout << endl; }