Hi, I am working on a small project where I need to implement barcode. I was considering the factory pattern since I am dealing with multiple barcodes UPCA, EAN13 etc. I am really having a problem getting this pattern. Here is my code
Public
Interface IBarcode
Function CalculateChecksumDigit(ByVal sBarcode As String) As Integer
ReadOnly Property CheckSumDigit() As Integer
End
Interface
Public
Interface IUpc
Inherits IBarcode
Property ManufactureCode() As String
Property ProductCode() As String
Property ProductType() As String
End
Interface
Public
Interface IEan
Inherits IBarcode
Property CountryCode() As String
Property ManufactureCode() As String
Property ProductCode() As String
End
Interface
Public
Class BarcodeUPCA12
Implements IUpc
Private _productType As String
Private _manufacturerCode As String
Private _productCode As String
Private _checksumDigit As String
Sub New()
_productType =
String.Empty
_manufacturerCode =
String.Empty
_productCode =
String.Empty
_checksumDigit =
String.Empty
End Sub
Public Function CalculateChecksumDigit(ByVal sBarcode As String) As Integer Implements IUpc.CalculateChecksumDigit
_productType = sBarcode.Substring(0, 1)
_manufacturerCode = sBarcode.Substring(1, 5)
_productCode = sBarcode.Substring(6, 5)
do calc....
Return Me._checksumDigit
End Function
Public ReadOnly Property CheckSumDigit() As Integer Implements IUpc.CheckSumDigit
Get
Return _checksumDigit
End Get
End Property
Public Property ManufactureCode() As String Implements IUpc.ManufactureCode
Get
Return _manufacturerCode
End Get
Set(ByVal value As String)
_manufacturerCode = value
End Set
End Property
Public Property ProductCode() As String Implements IUpc.ProductCode
Get
Return _productCode
End Get
Set(ByVal value As String)
_productCode = value
End Set
End Property
Public Property ProductType() As String Implements IUpc.ProductType
Get
Return _productType
End Get
Set(ByVal value As String)
_productType = value
End Set
End Property
End
Class
Public
Enum BarcodeType
UPCA12
EAN13
End
Enum
Public
Class BarcodeFactory
Public Shared Function CreateBarcode(ByVal barcodeType As BarcodeType) As IBarcode
Select Case barcodeType
Case Barcode.BarcodeType.UPCA12
Return New BarcodeUPCA12
End Select
Return Nothing
End Function
End
Class
Public
Class BarcodeEvaluator
Public Shared barcode As IBarcode
Public Function CalculateChecksumDigit(ByVal sBarcode As String) As Integer
Select Case sBarcode.Length
Case 14 Or 17
Return barcode.CalculateChecksumDigit(sBarcode)
End Select
End Function
Public Function Test() As String
Return "Hello"
End Function
End
Class
CLIENT USE -------------------------------------------------------------------------------
Imports
Barcode
Public
Class Form1
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim barcode As New BarcodeEvaluator
MsgBox(barcode.CalculateChecksumDigit(
"1233492213916"))
End Sub
End
Class
First off it doesn't work. Second - Is this how it should be done
Please advice. I am really trying to get this pattern thing.
2. Implement a single Provider which creates the instance of the barcode you are looking for.
3. Implement the UPCA, EAN13 as Classes which implement the methods in the interface specific to the standards and in addition implement the properties and classes specific to the standard.
