Question

I developing application using backround processes and MVP pattern.
Can I store states of processes (isCanceled, isStarted or isPaused) in ModelProcess (Model) like this:

public event EventHandler CancelChanged;
  bool isCanceled = false;
    public bool IsCanceled
    {
        get { return isCanceled; }
        set
        {
            isCanceled = value;
            if (isCanceled)
            {
                if (CancelChanged != null)
                {
                    CancelChanged(this, EventArgs.Empty);
                }
            }
        }
    }

Answer 1

Your setter will only call CancelChanged if isCanceled is being set to true, no matter if it has been false before. The following code will check if there is an actual change of the value, wich makes it idempotent.

set
{
    if (value != isCanceled)
    {
        isCanceled = value;
        if (CancelChanged != null)
        {
            CancelChanged(this, EventArgs.Empty);
        }
    }
}