[2008] My app has gone beserk. Application.Exit and RaiseEvent problems

[Simonta]

Hi folks.

I have an app which has been working fine for about 2 months. Yesterday, I carried out a maintenance session which was mainly simple bug fixing and moving my code into regions to help navigating through it. Along the way, 2 things have started happening which has totally broken my app.

MSDN states that Application.Exit does not cause the Form.Closed or Form.Closing events to fire.

http://msdn.microsoft.com/en-us/libr...it(VS.71).aspx

However, my Form.Closing event is firing immediately after Application.Exit which is in a button click handler on the form. The code is like this:

Private Sub cmdCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cmdCancel.Click

        If CurrentSite.SiteHasChanged(OldSite) Or CurrentSite.NewSite Then
            If MsgBox("Do you want to save your changes?", MsgBoxStyle.Question Or MsgBoxStyle.YesNo Or MsgBoxStyle.DefaultButton1, "Please confirm") = MsgBoxResult.Yes Then
                Me.Close()
            Else
                Application.Exit()
            End If
        Else
            Application.Exit()
        End If

    End Sub

When I step through, my code hits the Application.Exit through either path and the Form.Closing event fires immediately afterwards.

The second problem is that RaiseEvent inside my custom class has stopped working.

Here's how I declare an instance of the class in the main form class of my app:

Friend WithEvents CurrentSite As New DomainSite   ' the site currently being edited

Within the class, I have a callback delegate being called from a background worker thread which is carrying out a blocking task in the background to keep my UI responsive. The callback delegate gets called correctly at the end of the task and my code hits this line:

RaiseEvent HostNameChanged()

Back in the form, I have an event handler on the CurrentSite instance declared as:

    Private Sub CurrentSite_HostNameChanged() Handles CurrentSite.HostNameChanged
        UpdateNetworkConnectors()
        lblHostName.Text = CurrentSite.HostName
    End Sub

This has been working just fine for 2 months and just suddenly stopped. I have not changed the class declarations, instance declarations, scopes or constructors.

The third symptom is that clicking on the "View Application Events" button on the application properties page (I have enabled the Application Framework) usually presents templates of the application events. It no longer does, so I added a handler for UnhandledException manually. This does not fire either!

What on earth has gone wrong? Tearing my hair out. The only option I can see now is to create a new project and start copy/paste but the risk is too high if someone could guide me out of this pickle.

Help????

Cheers

[jmcilhinney]

Are you sure that it's the Closing event that is being raised and not the FormClosing event? They are two different events. In .NET 1.x only the Closing and Closed events existed and calling Application.Exit didn't raise either. From .NET 2.0 the Closing and Closed events still exist and the FormClosing and FormClosed events have been added. Calling application still doesn't raise the Closing or Closed events but it does raise the FormClosing and FormClosed events.

Make sure you read what is actually on the page because Form.Closing and FormClosing are absolutely NOT the same thing. Every dot is absolutely critical in programming.

[Simonta]

Hi J

Thanks for the response. BTW, I am very familiar with all of VB, VS and OOP - thanks for the tip about dots ;-)

As I understand it, Form.Closing was deprecated in .Net 2.0 and replaced with Form.FormClosing although it's still in the Forms namespace. Intellisense doesn't show Closing unless you enable deprecated members in options. I'm now confused by the MSDN docs on Application.Exit as it's not clear how to prevent form closing code executing after an app exit.

This leads me to conclude that I have a design problem. I'll go back to the white board and post back the outline of my solution...(in a nice .Net OOP fashion of course)

Cheers

[chris128]

From MSDN:

Exit raises the following events and performs the associated conditional actions:

A FormClosing event is raised for every form represented by the OpenForms property.

Whats confusing about that... It clearly states that the FormClosing event will be raised for all forms that are currently open. Am I missing something?

[Simonta]

There is a nice neat solution - staring at me!

The FormClosing handler is passed an instance of System.Windows.Forms.FormClosingEventArgs.

This gave me:

If e.CloseReason = CloseReason.UserClosing Then

Job done. I can now call routines out of my FormClosing event only if the user has closed the app and not for Application.Exit, killing from Taskman etc.

Back to the RaiseEvent issue - a little Googling suggests that this is a common problem although I still can't figure it out. Definitely didn't change any scopes or instance lifetimes.

Cheers