Class like Module without the Dim in VB.NET
Access of shared member, constant member, enum member or nested type, through an instance; qualifying expression will not be evaluated
On the last post Make a class like a module , I decided to present the module like a class. Is not something people use or know, but is good bring it to the front.
Check the previous code:
Public Class Module1 Public Shared iNumber As Integer End Class |
Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Dim oModule1 As Module1 'declare a fake class oModule1.iNumber = oModule1.iNumber + 1 'don't need to initiate the variable because is shared TextBox1.Text = oModule1.iNumber 'the variable keep raising each time youpress button1 End Sub Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load End Sub End Class |
If you place your cursor over the oModule1 (with the green line) , you could bring a little error message:
Access of shared member, constant member, enum member or nested type, through an instance; qualifying expression will not be evaluated. I am sure you seen this previously in your life. If not, this will be your first one.
So why the error message? Well this is my explanation. Normally, object need to use the new function to ask the computer the spare some space to store the data. Shared member, constant member, enum member and all the other stuff like them are not really stealing space on your computer. They are part of your program as a definition. They are stored somewhere in your computer while your program is running in 1 single place. When you close the program, those definitions will be disappeared.
I hope this is clear for you. I have a lot of practice, but I am not good to explain these thing. I haven’t study in computer science. My training is something little bit different.
Anyway, if you replace the oModule1 and replace it by the class name Module1, it will work perfectly. Yes! You are using a class and you haven’t set any variable or object with the new function. You could also delete the first line with the Dim oModule1 as Module1. This is only possible if your class use shared stuff (integer, string, function, methods …)
Here is what would look your class with the shared integer iNumber:
Your file Module1.vb stays the same:
Public Class Module1 Public Shared iNumber As Integer End Class |
Your Form.vb changes a little bit:
Public Class Form1 Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click Module1.iNumber = Module1.iNumber + 1 'don't need to initiate the variable because is shared TextBox1.Text = Module1.iNumber 'the variable keep raising each time youpress button1 End Sub End Class |
What I am showing here should work the same way in C#.NET because it uses the same library .NET Framework. I can’t tell you for sure if it will work in VB6. VB6 acts differently and is a half way from procedure-oriented programming and object oriented programming.
In VBA (Visual Basic for Application). I honestly haven’t even thought about trying doing strange things like this. VBA works like VB6, but VBA is a simplified Visual Basic and is dependent to the Main application (MS-Excel, MS-Word, AutoCAD, See Electrical Expert, Catia…)
0 Response to "Class like Module without the Dim"
Posting Komentar