How to declare a global variable

[sjh]

Hi,
I would like to have a global variable g_sAppName. I tried declaring it inside my main form (shown below), but it is not recognized in other forms. How do I declare a global variable?

Public Class frmMain
Inherits System.Windows.Forms.Form

Public m_sAppTitle = "My .NET application"

___________________________
Many thanks,
Susie

 

[Kris11]

You can create a Public Module and declare Public variables in it or Private variables with Public properties.

-Kris

 

[sjn78]

Aren't modules a thing of the past? You can pass the object or whatever is it by value or by reference between forms using proper OOP methodolgy.

 

[chiph]

Modules are still there in VB.NET, but the correct OO way to do it would be to create an object using the Singleton design pattern.

You do a Singleton in VB.NET like this:

Imports System 

Public Class Singleton
  Private Shared myInstance As Singleton

  Private Sub New() 
  End Sub 
  
  Public Shared Function GetInstance() As Singleton
    If myInstance Is Nothing Then
      myInstance = New Singleton()
    End If
    Return myInstance
  End Function
End Class

Note that the constructor is private, so other callers are not able to directly create a new instance of this class. They have to go through the public Shared function called GetInstance. This returns them a copy of the internal instance (creating one the first time thru).

This way, everyone gets the same instance, which is what you want in a global variable.

Chip H.


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