RaiseEvent issue

Hello,

I use the RaiseEvent method to indicate to some classes to clear their memory (setting members to nothing so the garbage collector can do its job).

I call it in the FormClosing event of a form, but, for some reasons the process won't continue after the RaiseEvent line:

Code:

---

Private Sub FormHorodateur_FormClosing(ByVal sender As Object, _
                                          ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
   
        m_grid = Nothing
      RaiseEvent OnNotification(New Notification(EnumNotificationType.DOCUMENT_CLOSING, Me.GetType.Name, Me.GetType.Name, Me.GetType()))
        Me.Dispose()
    End Sub

---

... and the form never closes. Do you have any idea ?
Thank you,

Loïc Bauduin Brunelle,
ing jr.

I've partially resolved my problem. There was a missing "RemoveHandler". But, there is still something strange: the first time I try to close my window, the RaiseEvent does not come back to its calling point, but the second time I hit the "X" button, the RaiseEvent works perfectly...

Just a guess here, try removing Me.Dispose() from your code and see what happens.

In fact, the first time it enters the FormClosing event, My.Dispose is not even executed. The track is lost in the first call to RaiseEvent (I set a breakpoint on My.Dispose and it only breaks the second time I tried to close my window).

You absolutely should not be calling Dispose in the FormClosing event handler. The reason the FormClosing event is raised is because the form is closing and closing a form disposes it. The FormClosing event is raised, the form is disposed and then the FormClosed event is raised.

This assumes that the form was displayed by calling Show. If it was displayed by calling ShowDialog then closing it does not dispose, but there's still no reason for you to explicitly call Dispose in the FormClosing event handler. In that case it is the resposibility of the code that called ShowDialog to dispose the form, which it should usually do with a Using block.

Ok thank you, I removed the call to Dispose... but I still have my problem: the first time I hit the "X" button, my form does not close!

Can you post your current code (including what is in the event handler that is executed from your OnNotification event) ?

Here's my sender:

Code:

---

Public Class GestionnaireNotification
   
    ' Cette classe n'est pas un gestionnaire proprement dit...
    ' elle ne sert qu'à dispatcher les notifications
    Sub Diffuser(ByVal _notification As Notification)
        RaiseEvent SurNotification(_notification)
    End Sub

    Delegate Sub SurNotif(ByVal _notification As Notification)
    Public Event SurNotification As SurNotif

End Class
'=========================================================

#Region "Notifications"
    Private m_gestionnaireNotification As GestionnaireNotification
    Public ReadOnly Property GesNotif() As GestionnaireNotification
        Get
            If m_gestionnaireNotification Is Nothing Then
                m_gestionnaireNotification = New GestionnaireNotification()
            End If
            Return m_gestionnaireNotification
        End Get
    End Property
#End Region
'=========================================================

    Public ReadOnly Property DocHoro() As DocumentHorodateur
        Get
            If m_documentHorodateur Is Nothing Then
                m_documentHorodateur = New DocumentHorodateur()
                m_documentHorodateur.Ouvrir()
            End If
            Return m_documentHorodateur
        End Get
    End Property
    Public Sub FermerDocHoro()
        m_documentHorodateur.Fermer()
        m_documentHorodateur = Nothing
    End Sub

---

And here is how I use the sender:

Code:

---

Public Class DocumentHorodateur
    Inherits Document

    Private m_CompagnieActive As CompagnieHorodateur
    Private m_TypeCalendrierActif As CalendrierType
...

    Public Overrides Sub Fermer()
        m_CompagnieActive = Nothing
        m_TypeCalendrierActif = Nothing
        MyBase.Fermer()
    End Sub
End Class
'=========================================================

Public MustInherit Class Document
    Implements IDocument

    ' Variables membres
    Protected m_tabGestionnaire As Hashtable
    Protected m_tabSousDocument As ArrayList
...

    Public Overridable Sub Fermer() Implements IDocument.Fermer
        ' Envoyer une notification comme quoi on ferme le document
        RemoveHandler GesNotif.SurNotification, AddressOf SurNotification
        GesNotif.Diffuser(New Notification(EnumNotificationType.FERMETURE_DOCUMENT, Me.GetType.Name, Me.GetType.Name, Me.GetType()))
        m_tabGestionnaire = Nothing
        m_tabSousDocument = Nothing
        ' Éventuellement, il faudrait vérifier s'il y a des objets à sauvegarder ...
    End Sub
...
End Class
'=========================================================

    Private Sub FormHorodateur_FormClosing(ByVal sender As Object, _
                                          ByVal e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
        ' Tester si on peut fermer la fenêtre
        Dim ob As Form = Application.OpenForms(GetType(FormCompagnieHorodateur).Name)
        If ob IsNot Nothing Then
            e.Cancel = True
            Exit Sub
        End If

        RemoveHandler GesNotif.SurNotification, AddressOf SurNotification
        m_grid = Nothing
        FermerDocHoro()
    End Sub

---

I got a lot of handlers... I can show you some of them (they follow the same "rules"):

Code:

---

Public MustInherit Class Document
    Implements IDocument

    ' Variables membres
    Protected m_tabGestionnaire As Hashtable
    Protected m_tabSousDocument As ArrayList

    Sub New()
        m_tabGestionnaire = New Hashtable
        m_tabSousDocument = New ArrayList
        AddHandler GesNotif.SurNotification, AddressOf SurNotification
    End Sub
...
    Public Overridable Sub SurNotification(ByVal _notification As Notification) Implements IDocument.SurNotification
        ' Si c'est une fermeture de document, vérifier dans les sous-documents si une référence est gardée
        If _notification.NotificationType = EnumNotificationType.FERMETURE_DOCUMENT Then
            For Each doc As Object In m_tabSousDocument
                If doc.GetType.Name = _notification.ObjetCle Then
                    m_tabSousDocument.Remove(doc)
                End If
            Next
        End If
    End Sub
End Class
'=========================================================

Public MustInherit Class GestionnaireObjet
    Implements IGestionnaireObjet

    ' Variables membres
    Private m_dernierIdTmp As Long
    Protected m_document As IDocument
    Protected m_tabObjet As ArrayList
    Protected m_typeObjet As Type
    Protected m_typeTri As EnumTriType

    ' Constructeur
    Sub New()
        m_dernierIdTmp = -1
        m_tabObjet = New ArrayList
        m_typeTri = EnumTriType.NULL

        AddHandler GesNotif.SurNotification, AddressOf SurNotification
    End Sub
...
    Public Overridable Sub SurNotification(ByVal _notification As Notification) Implements IGestionnaireObjet.SurNotification
        If _notification.ObjetType Is Document.GetType AndAlso _
          _notification.NotificationType = EnumNotificationType.FERMETURE_DOCUMENT Then
            For Each ob As Objet In m_tabObjet
                ob.MettreANothing()
            Next
            m_tabObjet = Nothing
            Document = Nothing
            RemoveHandler GesNotif.SurNotification, AddressOf SurNotification
        End If
    End Sub
End Class
'=========================================================

Public Class FormHorodateur
    Private m_grid As ControleurDeGrid

    Sub New()
        ' Cet appel est requis par le Concepteur Windows Form.
        InitializeComponent()

        ' Ajoutez une initialisation quelconque après l'appel InitializeComponent().
       
        ' Initialisation du Grid
        m_grid = New ControleurDeGrid(Me.Grid, False)
...
        ' Écouter les notifications pour mettre à jour les objets affichés
        AddHandler GesNotif.SurNotification, AddressOf SurNotification

        'CType(DocGen().RetournerGestionnaire(GetType(Texte)), GestionnaireTexte).InitialiserFenetre(Me)
    End Sub

 ...
    Private Sub SurNotification(ByVal _notification As Notification)
        ' On ne met à jour la fenêtre que s'il y a une modification BD ou qu'un objet est supprimé
        ' on ne met pas l'événement POST_SUPPRIME_DANS_BD parce que l'objet est encore en mémoire à ce moment
        If _notification.NotificationType <> EnumNotificationType.SUPPRIME AndAlso _
          _notification.NotificationType <> EnumNotificationType.POST_TELEVERSE_DANS_BD Then
            Exit Sub
        End If

        ' Le type d'objet doit être CompagnieHorodateur, ou personne horodateur si on affiche les employés
        Select Case _notification.ObjetType.Name
            Case GetType(CompagnieHorodateur).Name
                MiseAJourGrid()
            Case GetType(PersonneHorodateur).Name
                MiseAJourListe(m_grid.CelluleSelectionnee)
        End Select
    End Sub
End Class

---

I finaly found my problem: it was only an exception in one of my handlers. I'm still not used to those try/catch!

I guess this thread could be set to Resolved now.

If you use a Try/Catch block, you must always at least do something in the Catch block. At least put a Debug.Writeline there, or maybe even a messagebox, informing you of the error. If you're going to use Try/Catch without any error messages, you are going to miss errors and leave everyone wondering what the hell went wrong.

Also, you need to set your thread to resolved yourself. Just click on 'Mark Resolved' in the Thread Tools menu at the top.