From: jet@aloha.net
On Mon, 02 May 2005 23:30:25 GMT, "Iain Bishop" wrote:
>I'm trying to model objects for the following problem:
>
>A building site contains assemblies, each of which can contain other
>assemblies and/or materials.
>
>I have modelled this using a Site class, Assembly class, and Material class
>as follows...
>
>Site Class (clsSite):
>Option Explicit
>'General Details
>Public ProjectNumber As String
>Public SiteWBSCode As String
>Public SiteType As String
>Public LastUpdateFirstName As String
>Public LastUpdateSurname As String
>Public LastUpdateDate As Date
>Public TotalPriceOfAllMaterials As Double
>Public GeneralNotes As String
>'Contents of Site
>Public SiteAssemblies As clsAssemblies 'a collection class of clsAssembly
>Public SiteMaterials As clsMaterials 'a collection class of clsMaterial
>
>Assembly Class (clsAssembly):
>Option Explicit
>'General Details
>Public ID As Long
>Public QuantityRequested As Integer
>Public QuantityIssued As Integer
>'Contents
>Public AssemblyAssemblies As clsAssemblies 'a collection class of
>clsAssembly
>Public AssemblyMaterials As clsMaterials 'a collection class of clsMaterial
>
>Material Class (clsMaterial)
>Option Explicit
>'General Details
>Public InventoryCode As String
>Public Rate As Double
>Public QuantityRequested As Integer
>Public QuantityIssued As Integer
>Public TotalPrice As Double
>Public DateAmended As Date
>
>My questions are:
>1. Have I modelled the problem correctly?
The replies you receievd so far sound very good. An exploded Bill
Of Material / Product Structure generally has the financial standard
costs and labor hours regenerated at the end of every month, so I
see no reason why you cannot save some CPU time by *NOT* making your
subtotals methods instead of properties: the End Of Month Closing
routines will perform all the necessary calculations and update the
properties.
For example: the PRMS mid-frame application that runs on the AS/400
has standard labor, standard labor costs, material costs, and the
like as properties (values). At the end of every financial month the
Month End Close / Cost Build programs are run, and new values for
components and sub-assemblies are generated. This generally means
the financial module includes in the database the next/future costing
values, and historical values. The database also contains actual labor
hours, actual labor costs, actual material costs, etc., so that one
may forecast future costs.
> 2. There is the potential for an infinite hierarchy of Assemblies -
> is this ok?
Infinite is bad; finite is good. :-)
You must add a check that looks to see if an assembly's newly-added
component part is not the assembly itself, and (if the component
is a sub-assembly) check to see if any of the newly-added component
parts include the parent part. This is actually very easy to do.
A section of code from my Product Structure modual (changing my
news reader's word-wrap to 700 characters):
Private Sub txtParent_LostFocus()
Dim FindPN As String, sSQL As String, nodX As Node, TheDesc As String,
TheUM As String
FindPN = UCase$(Trim(txtParent.Text))
txtParent.Text = FindPN: ' A fuction that looks at the Product Master to
see if a part number exists
If FindPN = "" Then Exit Sub
MousePointer = 11
DoEvents
Dim de As Boolean
If ServerLocation = "" Then
de = DoesPNExist(FindPN, TheDesc, TheUM)
Else
de = DF.DoesPNExist(FindPN, TheDesc, TheUM): ' Internet server, use
Business Object
End If
If de = True Then
lblDesc.Caption = TheDesc
TreeView1.Nodes.Clear
Set nodX = TreeView1.Nodes.Add()
nodX.Expanded = True
nodX.Text = FindPN
nodX.Image = 1
nodX.SelectedImage = 3
nodX.Key = FindPN
nodX.Tag = 0
List1.AddItem nodX.Text
List2.AddItem nodX.Text
If ServerLocation = "" Then
Set Adodc1.Recordset = GetSMP("SELECT * FROM ProductStructure
WHERE Parent = '" & FindPN & "';")
Else
Set Adodc1.Recordset = DF.GetSMP("SELECT * FROM ProductStructure
WHERE Parent = '" & FindPN & "';"): ' database is on web server
End If
Do Until Adodc1.Recordset.EOF
Set nodX = TreeView1.Nodes.Add(1, tvwChild)
nodX.Text = Adodc1.Recordset!Child
nodX.Image = 2
nodX.Key = Adodc1.Recordset!Child
nodX.Parent = Adodc1.Recordset!Parent
nodX.SelectedImage = 3
nodX.Tag = 1
List1.AddItem " " & nodX.Text
List2.AddItem "SELECT * FROM ProductStructure WHERE Parent = '" &
FindPN & "' AND Child = '" & nodX.Text & "';"
Adodc1.Recordset.MoveNext
Loop
DoEvents
PopulateSubAssemblies
Else
lblDesc.Caption = "The parent assembly does not exist in the product
master."
End If
MousePointer = 0
DoEvents
End Sub
Private Sub PopulateSubAssemblies()
Dim nodX As Node, Child As String, Parent As String, Level As Long
Dim LookIndex As Long, LastKey As String, tl As Long, i As Long
Dim lBox As Long
LookIndex = 1
Do
LookIndex = LookIndex + 1
Parent = TreeView1.Nodes(LookIndex).Text
Level = TreeView1.Nodes(LookIndex).Tag
For i = 0 To List1.ListCount - 1
If Trim(List1.List(i)) = Parent Then
lBox = i
Exit For
End If
Next
If ServerLocation = "" Then
Set Adodc1.Recordset = GetSMP("SELECT * FROM ProductStructure
WHERE Parent = '" & Parent & "' ORDER BY Child;")
Else
Set Adodc1.Recordset = DF.GetSMP("SELECT * FROM ProductStructure
WHERE Parent = '" & Parent & "' ORDER BY Child;"): ' SMPBO
End If
If Adodc1.Recordset.EOF = False Then
TreeView1.Nodes(LookIndex).Image = 1
TreeView1.Nodes(LookIndex).Expanded = True
Adodc1.Recordset.MoveFirst
Do While Adodc1.Recordset.EOF = False
Child = Adodc1.Recordset!Child
Set nodX = TreeView1.Nodes.Add(Parent, tvwChild, , Child, 2, 3)
nodX.Tag = Level + 1
List1.AddItem String$((Level + 1) * 3, " ") & nodX.Text, lBox
+ 1
List2.AddItem "SELECT * FROM ProductStructure WHERE Parent =
'" & Parent & "' AND Child = '" & nodX.Text & "';", lBox + 1
Adodc1.Recordset.MoveNext
Loop
End If
If LookIndex = TreeView1.Nodes.Count Then Exit Do
Loop
btnReport.Enabled = True
End Sub
What my program does is first check to see if the database is
local, or if it is on a web server. It then checks to see if
the part number is in the Product Master; if it is, it checks
to see if it is an assembly: if it is not in the Product Structure,
it is assumed to be a component and not an assembly.
If the part number is in the Product Structure, it is an assembly.
[continued in next message]
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