classes to perform functions for many forms

[Guest]

I have alot of event procedures, variables and methods I do in many forms. I thought I'd try to call class functions to do them. I started with an extremely simple example. A start form has two buttons. One opens form1 the other form2. Click a button and it sets an integer in the class and opens the form. In each form 3 public integers are defined. Two have values. In the form1 load event I instantiate class1 and call the add procedure c = cls1.ad

In class1 the add function checks the integer. If 1 it instantiates form1, if 2 form2. Then it attempts to add frm.a + frm.b

Unsurprisingly, the project can't build, telling me that a and b are not members of class1

If I have to pass a and b, or set them as public integers in class1, then how is it possible to build classes that can do complicated things for many forms? There must be a way, because the dataform wizard does something like it

The code is below. Any help would be appreciated

polynomial5


Public Class StartFor
Inherits System.Windows.Forms.For
Dim cls1 As New Class

#Region " Windows Form Designer generated code

Private Sub btnForm1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnForm1.Clic
cls1.iForm =
Dim frm As New Form
frm.Show(
End Su

Private Sub btnForm2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnForm2.Clic
cls1.iForm =
Dim frm As New Form
frm.Show(
End Su
End Clas

Public Class Form
Inherits System.Windows.Forms.For
Public a As Integer =
Public b As Integer =
Public c As Intege

#Region " Windows Form Designer generated code

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Loa
Dim cls1 As New Class
c = cls1.Ad
MsgBox(c.ToString
End Su
End Clas

form 2 is almost identica

Public Class Class
Public iForm As Intege

Public Function Add() As Intege
Dim frm As For

Select Case iFor
Case
frm = New Form

Case
frm = New Form

Case Els
MsgBox("No such form"

End Selec

Add = frm.a + frm.

End Functio

End Class

 

[Thomas]

Dim frm As Form - this gives you a reference to a base form.
Your instaces - Form1 and Form2 are decendants of the base form, but adds
new properties and methods.
When you use the base class - Form - to work with them, you only have
access to the base properties and methods, not the one you've added.

Here's a quick example of what you are looking for:

Public Class Form1
....

Public Class Form2
....


Dim f1 as Form1 <---- must declare them using correct class - or typecast
them from a Form to a Form1 (or Form2) when needed
Dim f2 as Form2
Dim x = f1.a + f2.b


Other alternative is to create a Interface and have each form implement that
interface:

Dim f1 as IMyForm
Dim f2 as IMyForm

Dim x = f1.a + f2.b

I have alot of event procedures, variables and methods I do in many forms.

I thought I'd try to call class functions to do them. I started with an
extremely simple example. A start form has two buttons. One opens form1
the other form2. Click a button and it sets an integer in the class and
opens the form. In each form 3 public integers are defined. Two have
values. In the form1 load event I instantiate class1 and call the add
procedure c = cls1.add

In class1 the add function checks the integer. If 1 it instantiates

form1, if 2 form2. Then it attempts to add frm.a + frm.b.

Unsurprisingly, the project can't build, telling me that a and b are not members of class1.

If I have to pass a and b, or set them as public integers in class1, then

how is it possible to build classes that can do complicated things for many
forms? There must be a way, because the dataform wizard does something like
it.

The code is below. Any help would be appreciated.

polynomial5d



Public Class StartForm
Inherits System.Windows.Forms.Form
Dim cls1 As New Class1

#Region " Windows Form Designer generated code "


Private Sub btnForm1_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btnForm1.Click

cls1.iForm = 1
Dim frm As New Form1
frm.Show()
End Sub

Private Sub btnForm2_Click(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles btnForm2.Click

cls1.iForm = 2
Dim frm As New Form2
frm.Show()
End Sub
End Class

Public Class Form1
Inherits System.Windows.Forms.Form
Public a As Integer = 5
Public b As Integer = 6
Public c As Integer

#Region " Windows Form Designer generated code "

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As

System.EventArgs) Handles MyBase.Load

 

[Guest]

Thanks muchly. That answers my question. And while getting a class to do work for many forms remains much more difficult than in vb6, at least it's doable

polynomial5d

 

[Steve Moores]

Hi there,

You can also define class members as Shared, that way you don't have to
instantiate an instance of the class to use the public members you've set
up.

It's not a good practice, but it sort of mimics the direct
ClassX.FunctionName syntax you're use to in VB6.

Thanks muchly. That answers my question. And while getting a class to do

work for many forms remains much more difficult than in vb6, at least it's
doable.