CODEWITHSUNDEEP
vb.netclass-design
Maslow
Maslow

Reputation: 18746

Vb.net How can I hide this variable from the rest of the class?

Public Class frmMain
    Private p_dlgAdd As frmAdd = Nothing
    Public ReadOnly Property _dlgAdd As frmAdd
        Get
            If p_dlgAdd Is Nothing Then
                p_dlgAdd = New frmAdd()
            End If
            Return p_dlgAdd
        End Get
    End Property

    Public Sub DoStuff()
       ''// Should not touch p_dlgAdd
    End Sub
End Class

For a few types of objects I would prefer to initialize them only when needed (sql connection, mainframe connections, large forms), because some users only use very specific parts of the program (managers may use one mainframe to do what they want, regular users use another resource primarily).

Why the p_? I am thinking using p_ would help me not use or easily find in intellisense the variable instead of the property locally in that class. Then using _ alone in front of private properties or private variables that don't need to locally be accessed by a property.

What would be a good way to help prevent me from accidently accessing p_dlgAdd directly? Is this a good use for anonymous variables in 2008? (I don't have 2008 available at work yet, but they think we will have it soon)

Upvotes: 1

Views: 1515

Answers (4)

Derek Tomes
Derek Tomes

Reputation: 4007

This is what Static is for.

Public Class frmMain
    Public ReadOnly Property _dlgAdd As frmAdd
        Get
            Static dlgAdd As frmAdd = Nothing
            If dlgAdd Is Nothing Then
                dlgAdd = New frmAdd()
            End If
            Return dlgAdd
        End Get
    End Property

    Public Sub DoStuff()
       ' cannot touch dlgAdd
    End Sub
End Class

https://msdn.microsoft.com/en-us/library/z2cty7t8.aspx

Upvotes: 0

chyne
chyne

Reputation: 667

You can use the EditorBrowseableAttribute to hide a class member from Intellisense.

<EditorBrowsable(System.ComponentModel.EditorBrowsableState.Never)> _
Private p_dlgAdd As frmAdd = Nothing

The other option that comes to mind is using a static analysis tool like Gendarme to check for violations of "don't access the field directly" rule. Not sure if Gendarme already has an appropriate rule, but it is extensible (may not be worth the effort in your case, however).

Upvotes: 2

Daniel Fabian
Daniel Fabian

Reputation: 3838

What you always CAN do (but it might be an overkill in your case), would be the Following:

public class Base
{
    private frmAdd p_dlgAdd = null;
    protected frmAdd _dlgAdd 
    {
        get
        {
            if(p_dlgAdd == null)
                p_dlgAdd = new frmAdd();
            return p_dlgAdd;
        }
    }
}

In this way, your "p_dlgAdd" will not be accessible and _dlgAdd only in the derived class. But this only works if you can define/change the base type.

Upvotes: 0

DCNYAM
DCNYAM

Reputation: 12126

Honestly, I'm not familiar with anonymous variables. With that said, there is really no mechanism I know of to stop you from writing code to access a private variable from within the same class. Just pay attention to your code. If you want to put some sort of prefix on the variable to remind yourself, that is acceptable.

Upvotes: 0

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