Visual Basic Software Sampler/Visual_Basic_Software_Sampler_Visual_Basic_Programmers_Journal_June_1996.iso/issues/03mar96/code/p81lst1.txt

Text File | 1996-02-06 | 6KB | 280 lines

Listing 1 [[VB4]]

' Removes inventory from the system
' This is used when inventory is sold,
' damaged, or adjusted
' Parameters:
'    sInvItem        Product Number of the
'                    item
'    iNumRemoved        Number of the
'                        product removed from
'                        inventory
' Returns:
'    iTotal            Total number in
'                    inventory
Public Function _
    RemoveInventory(sInvItem As _
    String, iNumRemoved As Integer) As _
    Integer
Dim iCurrentTotal

    ' Retrieve the current inventory
    ' count from the collection
    iCurrentTotal = _
        Me.Item(sInvItem).Quantity

    ' Perform the subtraction
    iCurrentTotal = iCurrentTotal - _
        iNumRemoved

    ' Code here should ensure the total
    ' number in inventory is never < 0

    ' Code here could also check the
    ' reorder point and automatically
    ' reorder when an order point is
    ' reached

    ' Update the collection
    Me.Item(sInvItem).Quantity = _
        iCurrentTotal

    ' Return the total amount
    RemoveInventory = iCurrentTotal

End Function



Listing 2 [[vb4]]


Private Sub Class_Initialize()
    ' Create the collection of inventory
    ' items
    CollectProducts
End Sub

' Fills the collection with the products
Private Sub CollectProducts()
    ' This is the prototype code
    ' to create the data in the collection
    ' Normally this information would
    ' exist in a database
    Dim Item As New CItem

    Item.ProductID = "1"
    Item.ProductNumber = "WD-123"
    Item.ProductName = "Widgets"
    Item.Quantity = 16

    ' Add this one to the collection
    ' Using the product number
    ' as the key
    m_colItems.Add Item, _
        Item.ProductNumber

    ' Clear the reference
    Set Item = Nothing

    ' Set another one
    Item.ProductID = "2"
    Item.ProductNumber = "GG-123"
    Item.ProductName = "Gagets"
    Item.Quantity = 120

    ' Add this one to the collection
    ' Using the product number
    ' as the key
    m_colItems.Add Item, _
        Item.ProductNumber

End Sub



Listing 3  [[VB4]]

' Form Name:    frmInventory
' Author:        Deborah Kurata, InStep
'                Technologies
' Date:        December 10, 1995
' Description:     Inventory form.
' This is a little test form for the OLE
' server and NOT a good design for an
' inventory form!
'
' Revisions:
'
Option Explicit

' Private member variables
Private m_Inventory As CInventory

' Constants for the command butons
Const iCLOSE = 0
Const iRECEIVE = 1
Const iSELL = 2

Private Sub cboItems_Click()
    ' If the user selects an item
    ' clear the number received
    txtReceived.Text = ""

    ' Set the total in inventory as
    ' appropriate
    If cboItems.ListIndex <> -1 Then
        txtTotal.Text = m_Inventory.Item_
            (cboItems.ListIndex + _
            1).Quantity
    End If

    ' Ensure the button is disabled
    ' until a quantity is entered
    cmdInventory(iRECEIVE).Enabled = _
        False
    cmdInventory(iSELL).Enabled = False
End Sub

Private Sub cmdInventory_Click(Index _
    As Integer)
Dim iTotal As Integer
Dim sProductNumber As String

    Select Case Index

        Case iCLOSE
            Unload Me

        Case iRECEIVE
            ' Product number for the
            ' inventory item
            ' NOTE: combo's are 0 based,
            ' collections are 1 based
            sProductNumber = _
                m_Inventory.Item_
                (cboItems.ListIndex + _
                1).ProductNumber

            ' Add the defined amount to
            ' the inventory
            iTotal = m_Inventory._
                AddInventory_
                (sProductNumber, _
                Val(txtReceived.Text))
            If Err.Number <> 0 Then
                ' A more friendly error
                ' message would be
                ' displayed to the user
                ' here
                ' With a more detailed
                ' message printed to a
                ' log file
                MsgBox Err.Description
            End If

            ' Display the revised
            ' inventory amount on the
            ' screen
            txtTotal.Text = iTotal

        Case iSELL
            ' Product number for the
            ' inventory item
            ' NOTE: combo's are 0 based,
            ' collections are 1 based
            sProductNumber = _
                m_Inventory.Item_
                (cboItems.ListIndex + _
                1).ProductNumber

            ' Remove the defined amount
            ' from the inventory
            iTotal = _
                m_Inventory._
                RemoveInventory_
                (sProductNumber, _
                Val(txtReceived.Text))
            If Err.Number <> 0 Then
                ' A more friendly error
                ' message would be
                ' displayed to the user
                ' here
                ' With a more detailed
                ' message printed to a
                ' log file
                MsgBox Err.Description
            End If

            ' Display the revised
            ' inventory amount on the
            ' screen
            txtTotal.Text = iTotal
    End Select
End Sub

Private Sub Form_Load()
Dim colItems As New Collection
Dim lCount As Long

    ' Create only one instance of the
    ' inventory class
    Set m_Inventory = New CInventory
    If Err.Number <> 0 Then
        ' A more friendly error message
        ' would be displayed to the user
        ' here
        ' With a more detailed message
        ' printed to a log file
        MsgBox Err.Description
        Unload Me
        GoTo EXIT_Form_Load
    End If

    ' Fill the combo box with values
    For lCount = 1 To m_Inventory.Count
        With m_Inventory.Item(lCount)
            cboItems.AddItem _
                .ProductNumber & _
                Space(5) & .ProductName
        End With
    Next lCount

EXIT_Form_Load:
End Sub

Private Sub Form_Unload(Cancel As _
    Integer)
    ' Clear the instance
    Set m_Inventory = Nothing
End Sub

Private Sub txtReceived_Change()
    ' If there is an amount entered and
    ' the command button is disabled,
    ' enable it
    If txtReceived.Text <> "" And _
        cmdInventory(iRECEIVE).Enabled _
        = False Then
        cmdInventory(iRECEIVE).Enabled _
            = True
        cmdInventory(iSELL).Enabled _
            = True
    End If
End Sub

Private Sub _
    txtReceived_KeyPress(KeyAscii _
    As Integer)
    If (Chr$(KeyAscii) <> vbBack) And _
        (Not IsNumeric(Chr$(KeyAscii))) _
        Then
        Beep
        KeyAscii = 0
    End If
End Sub

Prog w/Class Listings    March 1996    page 5