Question

I have a method running in a seperate thread. The thread is created and started from a form in a windows application. If an exception is thrown from inside the thread, what is the best way to pass it back to the main application. Right now, I’m passing a reference to the main form into the thread, then invoking the method from the thread, and causing the method to be called by the main application thread. Is there a best practice way to do this because I’m not comfortable with how I’m doing it now.

Example of my form:

public class frmMyForm : System.Windows.Forms.Form {     /// <summary>     /// Create a thread     /// </summary>     /// <param name='sender'></param>     /// <param name='e'></param>     private void btnTest_Click(object sender, EventArgs e)     {         try         {             //Create and start the thread            ThreadExample pThreadExample = new ThreadExample(this);            pThreadExample.Start();         }         catch (Exception ex)         {             MessageBox.Show(ex.Message, Application.ProductName);         }     }      /// <summary>     /// Called from inside the thread      /// </summary>     /// <param name='ex'></param>     public void HandleError(Exception ex)     {         //Invoke a method in the GUI's main thread         this.Invoke(new ThreadExample.delThreadSafeTriggerScript(HandleError), new Object[] { ex });     }      private void __HandleError(Exception ex)     {         MessageBox.Show(ex.Message);     } } 

Example of my thread class:

public class ThreadExample {     public delegate void delThreadSafeHandleException(System.Exception ex);      private Thread thExample_m;      frmMyForm pForm_m;     private frmMyForm Form     {         get         {             return pForm_m;         }     }      public ThreadExample(frmMyForm pForm)     {         pForm_m = pForm;          thExample_m = new Thread(new ThreadStart(Main));         thExample_m.Name = 'Example Thread';     }      public void Start()     {         thExample_m.Start();     }      private void Main()     {         try         {             throw new Exception('Test');         }         catch (Exception ex)         {             Form.HandleException(ex);         }     } } 

Answer 1

So you’re using Invoke to marshall back to the UI thread, by the looks of it – which is exactly what you need to do. I’d personally use an Action<Exception> for simplicity’s sake, and possibly BeginInvoke instead of Invoke, but basically you’re doing the right thing.