Code snippet - 0005

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ericwsw Posted: 04-19-2005 9:26 AM

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Design Pattern - Singleton Pattern

The singleton pattern is one of the best-known patterns in software engineering. Essentially, a singleton is a class which only allows a single instance of itself to be created, and usually gives simple access to that instance.

Global Information Holder

Public Class Info

    Public Data1 As String
    Public Data2 As String
    Public Data3 As String
  
    ' Fields
    Private Shared instance As Info

    ' Constructor
    Protected Sub New()

    End Sub

    ' Methods
    Public Shared Function GetInstance() As Info

        ' Uses "Lazy initialization"
        If instance Is Nothing Then
            instance = New Info
        End If

        Return instance

    End Function

End Class

Declare

Dim C_info As Info = Info.GetInstance

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chid replied on 08-01-2005 10:20 PM

rated by 0 users

variation:

Global Information Holder

 Public Class Info

    Public Data1 As String
    Public Data2 As String
    Public Data3 As String

    ' Fields
    Private Shared _Instance As Info
    ' Constructor
    Protected Sub New()
    End Sub
    ' Shared Properties
    Public Shared Readonly Property Instance() As Info
 	Get        
	    ' Uses "Lazy initialization"
 	    If _Instance Is Nothing Then
                -Instance = New Info
            End If
            Return _Instance
        End Get    
    End Property
End Class
Declare
Dim C_info As Info = Info.Instance

-Mike