Composite Pattern

One-to-one relationship

One-to-many relationship

Example : Command

class Sensor
{
    private Command _command;

    public void SetCommand(Command cmd)
    {
        _command = cmd;
    }
    public void ActEvent()
    {
        _command.Do();
    }
}

class Command 
{
    public void Do()
    {
        // Some Action
    }
}

Example : Command

class Sensor
{
    private List<Command> _commandList;

    public void AddCommand(Command cmd)
    {
        _commandList.Add(cmd);
    }
    public void ActEvent()
    {
        foreach (var command in _commandList)
        {
            command.Do();
        }
    }
}

Example : Command

class Sensor
{
    private Command _command;

    public void SetCommand(Command cmd)
    {
        _command = cmd;
    }
    public void ActEvent()
    {
        command.Do();
    }
}

class Command 
{
    public virtual void Do()
    {
        // Some Action
    }
}

class CompositeCommand : Command
{
    private List<Command> _commands;
    public override void Do()
    {
        foreach (var command in _commands)
        {
            command.Do();
        }
    }
}