How to call the function of a sibling class, from a class within the other sibling class in C#

Question

I have been assigned to upgrade a home media system by enabling remote control of the room audio system through the internet. As it is a legacy system, I am unable to alter much of the architecture. Below is a simplified form of the program. The system is composed of a few main classes initialized in the Home_Media_System object.

class Home_Media_System
{

    Network _networkdata

    Speakers _speakers

    Lights  _lights

    Household_devices household_devices

}

class Speakers
{
    void Play_Audio();
}


class Network
{
    UdpReceiver udpReceiver
    UdpTransmitter udpTransmitter

}


class UdpReceiver
{
    void receive_audio_player_command()
    {
        if(playCommand)
            start_audio();
    }

    void start_audio()
    {
        //How do I call the Play_Audio() function in class Speakers
    }

}

class UdpTransmitter
{
    void send_response();
}

My problem is to call the Play_Audio() function after receiving the command in the UdpReceiver class WITHIN the Network class. I hope this clears up the question title, as it was pretty hard to explain in a single sentence.

Note that the main classes are initialized in the Home_Media_System. Right now I am thinking of using double event handlers, but I wonder if there is a more elegant way to do so.

Answer 1

This is some bad hierarchy you have and there is something definitely wrong with design. But just to answer this we can use events/delegates in C# to communicate between siblings via parent. So I will define a event at two places:

In your Network class and in UdpReceiver class and raise events when needed

public class Network
{
    private UdpReceiver udpReceiver;
    UdpTransmitter udpTransmitter
    public event EventHandler PlayAudioEvent;

    public void Network()
    {
        udpReceiver.PlayAudioEvent += PlayAudioEventHandler;

    }

    void PlayAudioEventHandler(object sender, EventArgs e)
    {
        if (PlayAudioEvent != null)
        {
            PlayAudioEvent(this, null);
        }
     }
}

public class UdpReceiver
{
     public event EventHandler PlayAudioEvent;
    void receive_audio_player_command()
    {
        if(playCommand)
            start_audio();
    }

    void start_audio()
    {
        //How do I call the Play_Audio() function in class Speakers
        if (PlayAudioEvent != null)
        {
            PlayAudioEvent(this, null);
        }
    }

}

public class Home_Media_System
{


        public void Home_Media_System()
        {
            _networkdata.PlayAudioEvent +=  PlayAudioEventHandler
        }

        void PlayAudioEventHandler(object sender, EventArgs e)
        {
            _speakers.PlayAudio();
        }

also make all your classes as public/internal and method also as public.