Generic BindingList.Sum Items.MyPropert y: howto?

[Pieter]

Hi,

I use a customized Generic List (VB.NET 2.0) inherited from BindingList(Of
T).

I made some methods in this BindingList, to allow me to do some standard
functions on the BindingList-Items.
One of them is for instance SumItems, which returns me the sum of a given
Property of all the Items in the List.

e.g.: MyBindingList.S umItems("Price" ) returns me the sum of all the prices
of my articles in the list.

But I would like to be able to access directly the Property's of the T-class
of my BindingList. It woudl be much much nicer if I could directly type in
the code editor MyBindingList.S umItems.Price, and that I can, while coding,
see al the proeprty's of my T-class after typing
"MyBindingList. SumItems."...

Because I use Generics I somehow think this should be possible, although I
don't find how...

Anybody has any ideas? Any help would be really appreciated!

Thanks a lot in advance,

Pieter

PS: My current SumItems-method:

Public Function SumItems(ByVal ColumnName As String) As Decimal
Dim properties As PropertyDescrip torCollection
Dim myProperty As PropertyDescrip tor
Dim decSum As Decimal = 0

Try
' Specify search columns
If (ColumnName Is Nothing) Then
Return Nothing
End If

' Get list to search
Dim lItems As List(Of T) = Me.Items

If Me.Count 0 Then
properties =
TypeDescriptor. GetProperties(M e.Items(0).GetT ype)
myProperty = properties.Find (ColumnName, True)

If myProperty Is Nothing Then
Throw New ArgumentExcepti on("Invalid Property Name.",
ColumnName)
Return 0
Exit Function
End If

' Traverse list for value
For Each it As T In lItems
'Dim value As String = CStr(myProperty .GetValue(item) )
decSum += CSng(myProperty .GetValue(it))
Next it
End If

Catch ex As Exception
Throw ex
End Try

Return decSum
End Function

[=?Utf-8?B?Q2lhcmFuIE8nJ0Rvbm5lbGw=?=]

You would need to have the Price property declared in an Interface or base
class that you force T to implement or inherit from. Otherwise it isnt
possible.

--
Ciaran O''Donnell
http://wannabedeveloper.spaces.live.com
"Pieter" wrote:

Hi,

I use a customized Generic List (VB.NET 2.0) inherited from BindingList(Of
T).

I made some methods in this BindingList, to allow me to do some standard
functions on the BindingList-Items.
One of them is for instance SumItems, which returns me the sum of a given
Property of all the Items in the List.

e.g.: MyBindingList.S umItems("Price" ) returns me the sum of all the prices
of my articles in the list.

But I would like to be able to access directly the Property's of the T-class
of my BindingList. It woudl be much much nicer if I could directly type in
the code editor MyBindingList.S umItems.Price, and that I can, while coding,
see al the proeprty's of my T-class after typing
"MyBindingList. SumItems."...

Because I use Generics I somehow think this should be possible, although I
don't find how...

Anybody has any ideas? Any help would be really appreciated!

Thanks a lot in advance,

Pieter

PS: My current SumItems-method:

Public Function SumItems(ByVal ColumnName As String) As Decimal
Dim properties As PropertyDescrip torCollection
Dim myProperty As PropertyDescrip tor
Dim decSum As Decimal = 0

Try
' Specify search columns
If (ColumnName Is Nothing) Then
Return Nothing
End If

' Get list to search
Dim lItems As List(Of T) = Me.Items

If Me.Count 0 Then
properties =
TypeDescriptor. GetProperties(M e.Items(0).GetT ype)
myProperty = properties.Find (ColumnName, True)

If myProperty Is Nothing Then
Throw New ArgumentExcepti on("Invalid Property Name.",
ColumnName)
Return 0
Exit Function
End If

' Traverse list for value
For Each it As T In lItems
'Dim value As String = CStr(myProperty .GetValue(item) )
decSum += CSng(myProperty .GetValue(it))
Next it
End If

Catch ex As Exception
Throw ex
End Try

Return decSum
End Function