timer_fizzbuzz.cpp

A simple demonstration of using timers.This example creates and event loop and starts two timers to print fizz and buzz every 3 respective 5 seconds.

The user can also configure a third timer via stdin to print woof.

This example assumes you already understand the events.cpp example.

#include <libfilezilla/event_handler.hpp>
#include <libfilezilla/time.hpp>

#include <iostream>
#include <string>

struct interval_change_type;
typedef fz::simple_event<interval_change_type, fz::duration> interval_change;

class fizzbuzz final : public fz::event_handler
{
public:
    fizzbuzz(fz::event_loop& loop)
        : fz::event_handler(loop)
    {
        // Start two periodic timers
        fizz_ = add_timer(fz::duration::from_seconds(3), false);
        buzz_ = add_timer(fz::duration::from_seconds(5), false);
    }

    virtual ~fizzbuzz()
    {
        // This _MUST_ be called to avoid a race so that operator()(fz::event_base const&) is not called on a partially destructed object.
        remove_handler();
    }

private:
    virtual void operator()(fz::event_base const& ev)
    {
        // Dispatch the event to the correct function.
        fz::dispatch<fz::timer_event, interval_change>(ev, this, &fizzbuzz::on_timer, &fizzbuzz::on_interval_change);
    }

    void on_interval_change(fz::duration interval)
    {
        // We got told to change the woof interval.
        stop_timer(woof_);
        woof_ = add_timer(interval, false);
    }

    void on_timer(fz::timer_id const& id)
    {
        if (id == fizz_) {
            std::cout << "fizz" << std::endl;
        }
        else if (id == buzz_) {
            std::cout << "buzz" << std::endl;
        }
        else if (id == woof_) {
            std::cout << "woof" << std::endl;
        }
    }

    fz::timer_id fizz_{};
    fz::timer_id buzz_{};
    fz::timer_id woof_{};
};

int main()
{
    // Start an event loop and add a handler.
    fz::event_loop loop;
    fizzbuzz fb(loop);

    std::cout << "Enter interval in seconds for the woof timer or 0 to stop program." << std::endl;

    // Read numbers from stdin until reading fails or a 0 is entered
    int seconds;
    do {
        std::cin >> seconds;
        if (std::cin.good() && seconds > 0) {
            // Got a new interval, send to handler
            fb.send_event<interval_change>(fz::duration::from_seconds(seconds));
        }
    }
    while (std::cin.good() && seconds != 0);

    return 0;
}