Question

I have a windows form app, and a class which is called Game.

Let’s say Game class has an attribute counter, and i do some calculations and change counter in that class. So i want to return a text to the form whenever counter changes, and then assign it to a label on the form.

Can i do it with an event handler that returns type string ? Since i have to listen it and return something whenever something happens.

Thanks in advance.

Answer 1

Yes you can :p

A proper way of doing this is as follow (INotifyPropertyChanged will simply tell you what property has changed and doesn’t return the actual value, but is also a good way to go):

class CountArgs:EventArgs
{
   public int Count{get;set;} 

    public CountArgs(int c) { 
        Count = c; 
    }
}

class Game
{

   public event EventHandler<CountArgs> CountChanged; // it is possible to define your own delegate here.
   int count;
   public int Count
   {
      get { return count;}
      set { 
            if (count != value) // Only raise the event if the value changes
            {
                 count = value;
                 RaiseCountChangedEvent(value);
            }
   }  
   void RaiseCountChangedEvent(int c)
   {
      if (CountChanged != null) // Check that at least one object is listening to the event
      {
          CountChanged(this,new CountArgs(c));
      }
   }
}

Hopefully, I didn’t make any syntax mistake as I coded this by head 🙂 But you get the idea.
You can register your form with the even and listen to it as you would do with any control.