Simple event raising/handling.

[Moorzee]

I create a proj with a form containing a button and 3 textboxes.
I declare an event named ValidateCont passing a control as a parameter. For each textboxes validate method( i have causes validation true on each) i raise the ValidateCont passing the textbox as the param.

I add a class module to the proj and declare my form in here with events and add code in the event handler of this to do something but this is never executed. What have I done wrong?

Cheers.

[DigiRev]

I don't understand exactly what you mean, can you post your code?

[Moorzee]

Hi Dig

Form code

Option Explicit

Public Event ButtonClicked()
Public Event ValidateCont(objCont As Control, ByRef Cancel As Boolean)

Private Sub txtAge_Validate(Cancel As Boolean)
    RaiseEvent ValidateCont(Me.txtAge, Cancel)
End Sub

Private Sub txtFirstname_Validate(Cancel As Boolean)
    RaiseEvent ValidateCont(Me.txtFirstname, Cancel)
End Sub

Private Sub txtSurname_Validate(Cancel As Boolean)
    RaiseEvent ValidateCont(Me.txtSurname, Cancel)
End Sub

Handling class code

Option Explicit

Dim WithEvents f As frmMaint

Private Sub Class_Initialize()
    Set f = New frmMaint
    f.Show
End Sub

Private Sub f_ButtonClicked()
    End
End Sub


Private Sub f_ValidateCont(objCont As Control, ByRef Cancel As Boolean)
    Select Case LCase(objCont.Name)
        Case "txtfirstname"
            If Len(objCont.Text) < 2 Then
                Cancel = True
            End If
        Case "txtsurname"
            If Len(objCont.Text) < 3 Then
                Cancel = True
            End If
        Case "txtage"
            If IsNumeric(objCont.Text) = False Then
                Cancel = True
            End If
    End Select
End Sub

[leinad31]

The class should also declare and raise the event in order to pass it.

[Moorzee]

The class should also declare and raise the event in order to pass it.

But I want the class to handle the forms event?

[icanflyiwillfly]

You can create custom events only in user defined classes.

But what you want can be achieved another way. Whenever you wish to raise the ValidateCont event, call the <class name>.ValidateCont(...) function instead.

[Moorzee]

You can create custom events only in user defined classes.

But what you want can be achieved another way. Whenever you wish to raise the ValidateCont event, call the <class name>.ValidateCont(...) function instead.

The why does a form allow me to declare and raise an event?

[icanflyiwillfly]

Your are right, but it is meant to be used the other way -- "declare and raise the events in a class, and catch them in a form or another class".

[Moorzee]

But if I wanted business logic, validation etc.. outside of the form I need to be able to raise an event from my form and handle it in a class?

What if I want my form to able to tell the outside world when a button's been clicked or textbox validate event is fired not have code inside form to handle? This must be do-able surely?

[icanflyiwillfly]

You can also declare and raise events in a custom-control. A custom control is also like a class, though it has a graphical interface.

The reason you can't raise events from a form is that a form, eg. Form1 in your project is an instance of a class Form. You may declare events in this Form class. But since you haven't created the Form class, you can't modify it.

[icanflyiwillfly]

What if I want my form to able to tell the outside world when a button's been clicked or textbox validate event is fired not have code inside form to handle? This must be do-able surely?

Then you can create a custom user-control, add validation functions into that user-control, and then use those controls in the form.

Otherwise as I mentioned, raising an event is just like calling a function. When catch the event in the form, just call the function in the class.

[Moorzee]

Why in the code posted above does the f_ValidateCont not get triggered when I raise the event from the form created in the class modules' initialize?

[Moorzee]

Is anyone able to tell me why the event is not handled in my class above?