Question

I’ve tried to use .Find() methode and was successfully. But I can not understand how to work with FindAll to receive all items matching on a “flexible” keyword (in my case this keywords is called ClassGuid).

Public Class clsFindConnection
Private Delegate Function ConMatchDelegate(ByVal con As PropertyConnection, ByVal ClassGuid As String) As Boolean



    Public Function GetPropertyConnectionsByGuid(ByVal ClassGuid As String, ByVal LBaseConnections As List(Of PropertyConnection)) As List(Of PropertyConnection)
        Dim Res As List(Of PropertyConnection)
        Dim dl As New ConMatchDelegate(AddressOf ConnectionFromMatch)
        Res = LBaseConnections.FindAll(dl)'<-- ERROR. Can not work because delegate is only using a single item. 
        Return Res
    End Function

    Friend Function ConnectionFromMatch(ByVal con As PropertyConnection, ByVal ClassGuid As String) As Boolean
        If con.PaintPluginFrom Is Nothing Then Return False
        If con.PaintPluginFrom.Plugin Is Nothing Then Return False
        If con.PaintPluginFrom.Plugin.Guid = ClassGuid Then Return True
        Return False
    End Function
End Class

How can this be used?

Answer 1

Use a lambda expression to pass the second parameter:

Res = LBaseConnections.FindAll(Function(con) ConnectionFromMatch(con, ClassGuid))

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EDIT to answer your comment:

FindAll takes a Predicate(Of T) (Predicate(Of PropertyConnection) in your case), so you can’t pass a ConMatchDelegate to it, since the signature is not compatible. So I create a Predicate(Of PropertyConnection) using an anonymous method. This will probably be more understandable:

Dim filter As Predicate(Of PropertyConnection) = Function(con) ConnectionFromMatch(con, ClassGuid)
Res = LBaseConnections.FindAll(filter)