event_queue.cpp

#include <iostream>
#include <queue>

struct PlayMessage
{
    int soundId;
    int volume;
};

class Audio
{
public:
    static void update()
    {
        if (messageQueue.empty())
        {
            return;
        }
        int soundId = messageQueue.front().soundId;
        std::cout << "start sound: " << soundId << std::endl;
        messageQueue.pop();
    }

    static void playSound(int soundId, int volume)
    {
        messageQueue.push({soundId, volume});
    }

private:
    static std::queue<PlayMessage> messageQueue;
};

std::queue<PlayMessage> Audio::messageQueue;

int main()
{
    Audio::playSound(0, 1);
    Audio::playSound(1, 1);
    Audio::update(); // start sound: 0
    Audio::update(); // start sound: 1
    Audio::update(); // no output
}

Game Programming Patterns, Chapter 15 Event Queue