Access form controls from a general module in .net

[Ergo60]

In VB6 I could use the following code in a general module to change the text in a textbox on a form

frmMain.tbText.Text = "Hello World"

but this does not work in .NET. I have changed the Modifiers property to Public for each control I want access to, but they still do not show up in the intellisense listing.

Any help?

[Cander]

you need to add a parameter to your routine of the Form class.

ie

mysub(ByVal myform As Form)

then when you call it from code in you form, just pass Me

mysub(Me)

this is the OOP way of doing things.

[Ergo60]

OK

I did try this and it seems to work, but is it correct practice?

dim TfrmMain as frmMain

set controls using TfrmMain reference

TfrmMain = nothing

[Cander]

yes it is. VB .NET is a true OOP language now, and OOP handles objects very differently as you dont have these persistant pointers acrosss process'. If that makes any sense.

[Ergo60]

So can I assume that when I execute the following code that it is just creating a new reference to the existing form? I would have thought that it was creating a new copy, and therefore wasting resources.

What is it doing? Creating a new reference, or creating a new copy?

[Magiaus]

in vb6 everthing was a copy of a copy of a copy because it was passed byval by default .net has integrated with the rest of the programming world and now passes a refreance so be careful what you do it isn't a copy unless you

Public Sub mSub(ByVal getCopyByVal as Object)

so Cander is making a copy and your code is ByRef i think

Cander what do you think = is = after all

[Ergo60]

I actually found out that the statement

Dim TfrmMain as frmMain

did not work. While it did create a variable of the frmMain type, it was still nothing, so it did not raise any errors, but it also did not do anything.

I then changed it to Dim TfrmMain as New frmMain, and while this worked, it caused an endless loop of form creations, since I have initialization code in the area where the for is created.

I did however find some code that microsoft uses when it converts an older VB6 project to .Net. This code creates a new property called defInstance that essentially does the same thing, but also defines a new boolean member variable that you can check to see if you are creating the initial form or just wanting a copy.

While this is all well and good, it does seem to create a new instance of it, so when I am setting the values I am setting the ones of the copy, and then when I dispose of it the origional ones are still the old values.

I will pst code in a few so that you can see what I am doing. I also do a similar thing with charting objects, but that actually works. I will post that code as well.

Thanks

[Ergo60]

OK here goes the code part, sorry if this gets to long:

Here is the Microsoft code:

#Region "Upgrade Support "
  Private Shared m_vb6FormDefInstance As frmMain
  Private Shared m_InitializingDefInstance As Boolean

  Public Shared Property DefInstance() As frmMain
    Get
      If m_vb6FormDefInstance Is Nothing OrElse    
         m_vb6FormDefInstance.IsDisposed Then
         m_InitializingDefInstance = True
         m_vb6FormDefInstance = New frmMain()
         m_InitializingDefInstance = False
      End If
      DefInstance = m_vb6FormDefInstance
    End Get
    Set(ByVal Value As frmMain)
      m_vb6FormDefInstance = Value
    End Set
  End Property
#End Region

You can then use the m_InitializingDefInstance variable in your for initialize code to bypass any routines that should not be run on the new instance.


In the code that I have in a General module I use it like this.

frmMain.DefInstance.tbMinScale1.Text = GetSetting("ProdTest", "Settings", "ScaleMin1", "0")
frmMain.DefInstance.tbMaxScale1.Text = GetSetting("ProdTest", "Settings", "ScaleMax1", "5")

I have verified that the return value from GetSetting is correct, but it is not showing up on the form.

I also have a generic status label on the main form that I use all over my code to inform the user what is going on. In VB6 it was easy to do, but .Net makes it a little harder. There has to be a way of making the form referance a public variable, right?

Without passing it around all the time, there are many places where I need access outside of the main form code, so I would not have the reference to pass.

thanks