Question

I have an Exception Handling project in my application that can be called from anywhere to show the user there is a problem with with system. Everything works great when the call is made from somewhere in the UI as expected. When I make calls from no UI parts of the application everything freezes. I have the code wrapped in the thread safe calls and when stepping through they don’t require the Invoke call. Any help is greatly appreciated. Code below:

Inside the form

    void err_DispEvent(string text)
    {
        if (InvokeRequired)
        {
            Invoke(new Error.DisplayDelegate(err_DispEvent), new object [] {text});
        }
        else
        {
            this.Show();
        }        
    }

Call from the class

public void FaultError(string errorMsg)
    {
        FaultForm fform = new FaultForm(errorMsg, "Internal Fault");
        if (this.dispEvent != null)
        {
            dispEvent(errorMsg);
        }
    }

    public event DisplayDelegate DispEvent
    {
        add { dispEvent += value; }
        remove { dispEvent -= value; }
    }

    private event DisplayDelegate dispEvent;

    public delegate void DisplayDelegate(string text);

Sample of how the class is used in the application

ECDUExceptions.Error newError = ECDUExceptions.Error.getInstance();
newError.FaultError("Heater is not responding to function calls, it has been turned off");

Answer 1

Some information when re-invoking methods:

1. Use BeginInvoke(...) instead of Invoke(...) as this will not wait for the call to finish, and so won’t freeze the calling thread.

2. Use an Action when re-invoking. So in your case, you could change your invocation to:

   BeginInvoke(new Action<string>(err_DispEvent), text);