[AccessD] Doing some thing the class way... was Toolbar

[Bill Benson]

John what is the
   function form_OnOpen

and where is that? It appears to be hanging out below a sentence that says
what you are doing in the onOpen event of your form.

I have more response prepared but wanted to ask this separately.

On Sat, Jan 29, 2022 at 8:57 AM John Colby <jwcolby at gmail.com> wrote:

> Bill,
>
> If I create my own class to "wrap" an object, I have to dimension a
> variable to hold a pointer to my class after I open it.  Let's assume I
> want to create a clsFrm to wrap my form and sink events from my form.
>
> 1) I create my clsFrm.
> 2) In the header of my clsFrm I create a variable
>
> dim frm as form
>
> 3) I create an Init function
>
> function finit(lfrm as form)
>    set frm = lfrm
> end function
>
> Back in the header of my form's cbf module I dim a pointer to my class
>
> dim gclsFrm as clsFrm
>
> In The OnOpen of my form I instantiate my class
>
> function form_OnOpen()
>
>
>
>
> On Sat, Jan 29, 2022 at 7:38 AM Bill Benson <bensonforums at gmail.com>
> wrote:
>
> > John - I need to ask for clarification on a few definitions and
> procedures
> > in your explanation.
> >
> > 1. What does CBF stand for?
> > 2. Where and how do you create instances of the class module you are
> > assigning forms to?
> >
> > I have a new database with only one form named Form1, which has no code
> in
> > its code module, and which has had added to it, in design view before I
> > closed and saved it, a single control (command button) named Command0. I
> > will next write some code in a class module I named clsForm, and a
> > procedure named LoadForms in a standard module named Module1; I will
> single
> > step through LoadForms and report on intermediary results. As I will hit
> a
> > runtime error very quickly, I will ask you some questions.
> >
> > 'clsForm
> > Option Compare Database
> > Option Explicit
> > Public WithEvents MyForm As Form
> >    Private Sub MyForm_Load()
> >        g_i_IncrementForms = g_i_IncrementForms + 1
> >        MsgBox "Instance " & g_i_IncrementForms & " of Form_" &
> > Me.MyForm.Name & " was unloaded"
> >    End Sub
> >
> >    Private Sub MyForm_Unload(Cancel As Integer)
> >        MsgBox "Instance " & g_i_IncrementForms & " of Form_" &
> > Me.MyForm.Name & " was unloaded"
> >    End Sub
> >
> > 'Module1
> > Option Compare Database
> > Option Explicit
> > Public g_i_IncrementForms   As Long
> > Public g_col_Forms          As Collection
> > Sub LoadForms()
> >    Dim clsForm     As clsForm
> >    Dim Form        As Object
> >    Dim Forms       As Object
> >
> >    Set Forms = Application.CurrentProject.AllForms
> >    For Each Form In Forms
> >       Set clsForm = New clsForm
> >       g_i_IncrementForms = 0
> >       Set clsForm.MyForm = Form
> >       If g_col_Forms Is Nothing Then
> >         Set g_col_Forms = New Collection
> >       End If
> >       g_col_Forms.Add clsForm
> >    Next
> > End Sub
> >
> > Single-Stepping through Module1.LoadForms: Before the line Set
> > clsForm.MyForm = Form, the immediate window can give me these results:
> >    ?TypeName(Forms)
> >      AllObjects
> >    ?TypeOf Forms is AllForms
> >      True
> >    ?TypeOf Form is Object
> >      True
> >    ?TypeOf Form is Form
> >      False
> >    ?Forms(0).name
> >      Form1
> >
> > Some things to note:
> >     In the construction above, Form is declared as Object.
> >     The line Set clsForm.MyForm = Form, will throw a runtime error.
> >
> > If instead this declaration had been used
> >    Dim Form        As Form
> >
> > then this line would have produced a runtime error:
> >    For Each Form In Forms
> >
> > Therefore, in order to have some kind of collection to loop *prior* to
> > opening any forms, I have to deal with the AllObjects class with members
> of
> > type Object. Declaring the MyForm object in the clsForm class module is
> > what causes the assignment  Set clsForm.MyForm = Form to result in a type
> > mismatch error.
> >
> > So given my results, I concluded - you will apparently tell me WRONGLY -
> > that using class modules to house a Form's events was not possible until
> > the Form itself has been opened.
> >
> > So in order for me to understand what you are implying by stating the
> class
> > module approach can be used to hold the Form's events, I need you to show
> > me some code that will create an instance of clsForm for each Form type
> > access object. That will enable me to apply your methods. Your
> explanation
> > so far confuses me, since you talk about declaring things "in the Form
> > header". What Form header, in the code module of the Form? If that is so,
> > then the Form has to be opened in order for those objects to get assigned
> > something in memory. Until then, I assume they are either allocated some
> > memory, or are in fact nothing at all, prior to a particular Form
> opening.