"Paul" <P***@discussions.microsoft.com> wrote in message
news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
>   I have a base class called DataElement.  Then I have several classes
> that
> inherit from this class, such as Aor, Aor0, plus a bunch more.  Each of
> these
> classes that inherit from DataElement have a Shared Function and an
> instance
> method that returns a List(of Aor) or List(of Aor0), etc., see below for
> basic class structures.
>
> Public Class DataElement
> End Class
>
> Public Class Aor
> Inherits DataElement
>
>   Public Function LoadFullList() as List(of Aor)
>      Return GetFullList()
>   End Function
>
>   Public Shared Function GetFullList() as List(of Aor)
>   End Function
>
> End Class
>
> Then someplace else in the my application I have a screen that works with
> DataElements and needs to call the GetFullList or LoadFullList and I can't
> figure out a way to accomplish this.  I could put the LoadFullList method
> into the DataElement class, but then the return type would have to be
> List(of
> DataElement) and then I wouldn't be able to handle the returned list in
> the
> method that I want because it wouldn't be List(of Aor).
>
> Can someone help me out here.

"Kevin Spencer" wrote:

> Hi Paul,
>
> Since Aor is derived from DataElement, it certainly would be able to return
> a List(of Aor). It could return a list of any type that inherits
> DataElement.
>
> --
> HTH,
>
> Kevin Spencer
> Microsoft MVP
> ..Net Developer
> A watched clock never boils.
>
> "Paul" <P***@discussions.microsoft.com> wrote in message
> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
> >   I have a base class called DataElement.  Then I have several classes
> > that
> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each of
> > these
> > classes that inherit from DataElement have a Shared Function and an
> > instance
> > method that returns a List(of Aor) or List(of Aor0), etc., see below for
> > basic class structures.
> >
> > Public Class DataElement
> > End Class
> >
> > Public Class Aor
> > Inherits DataElement
> >
> >   Public Function LoadFullList() as List(of Aor)
> >      Return GetFullList()
> >   End Function
> >
> >   Public Shared Function GetFullList() as List(of Aor)
> >   End Function
> >
> > End Class
> >
> > Then someplace else in the my application I have a screen that works with
> > DataElements and needs to call the GetFullList or LoadFullList and I can't
> > figure out a way to accomplish this.  I could put the LoadFullList method
> > into the DataElement class, but then the return type would have to be
> > List(of
> > DataElement) and then I wouldn't be able to handle the returned list in
> > the
> > method that I want because it wouldn't be List(of Aor).
> >
> > Can someone help me out here.
>
>
>

"Paul" <P***@discussions.microsoft.com> wrote in message
news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
> The is not what my problem is.  My problem in that I have wanother
> procedure
> that is trying to deal with this list, but it is trying to do it at a
> dataelement level
>
> Public Sub DoSomethingWithList(element as DataElement)
>   dim list as List(of DataElement = element.LoadFullList()
> End Sub
>
> Because element.LoadFullList() returns list(of Aor) it cannot be converted
> to List(of DataElement).
>
> "Kevin Spencer" wrote:
>
>> Hi Paul,
>>
>> Since Aor is derived from DataElement, it certainly would be able to
>> return
>> a List(of Aor). It could return a list of any type that inherits
>> DataElement.
>>
>> --
>> HTH,
>>
>> Kevin Spencer
>> Microsoft MVP
>> ..Net Developer
>> A watched clock never boils.
>>
>> "Paul" <P***@discussions.microsoft.com> wrote in message
>> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
>> >   I have a base class called DataElement.  Then I have several classes
>> > that
>> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each of
>> > these
>> > classes that inherit from DataElement have a Shared Function and an
>> > instance
>> > method that returns a List(of Aor) or List(of Aor0), etc., see below
>> > for
>> > basic class structures.
>> >
>> > Public Class DataElement
>> > End Class
>> >
>> > Public Class Aor
>> > Inherits DataElement
>> >
>> >   Public Function LoadFullList() as List(of Aor)
>> >      Return GetFullList()
>> >   End Function
>> >
>> >   Public Shared Function GetFullList() as List(of Aor)
>> >   End Function
>> >
>> > End Class
>> >
>> > Then someplace else in the my application I have a screen that works
>> > with
>> > DataElements and needs to call the GetFullList or LoadFullList and I
>> > can't
>> > figure out a way to accomplish this.  I could put the LoadFullList
>> > method
>> > into the DataElement class, but then the return type would have to be
>> > List(of
>> > DataElement) and then I wouldn't be able to handle the returned list in
>> > the
>> > method that I want because it wouldn't be List(of Aor).
>> >
>> > Can someone help me out here.
>>
>>
>>

"Kevin Spencer" wrote:

> Hi Paul,
>
> Forgive me for not recognizing the Generic syntax in your posts. I haven't
> delved into the VB.Net Generic syntax until now. Now that I understand your
> dilemma fully, I think I can help you resolve your issue.
>
> If you want to take full advantage of Generics, you need not create a base
> class and a number of inherited classes. You can define a single class with
> Generic  methods that takes type parameters. Example:
>
> Public Class DataElement
>
>   Public Function LoadFullList (Of ListType) ( ) as ListType
>      Return GetFullList (Of ListType) ( )
>   End Function
>
>   Public Shared Function GetFullList() (Of ListType)  as ListType
>   End Function
>
> End Class
>
> The class is not Generic, but both methods are. You can then call either
> method, passing the type of return value that you want from it, and it will
> return that type.
>
> I'm still not sure I'm understanding your question fully, though. Let me
> know if I've missed something.
>
> --
> HTH,
>
> Kevin Spencer
> Microsoft MVP
> ..Net Developer
> A watched clock never boils.
>
> "Paul" <P***@discussions.microsoft.com> wrote in message
> news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
> > The is not what my problem is.  My problem in that I have wanother
> > procedure
> > that is trying to deal with this list, but it is trying to do it at a
> > dataelement level
> >
> > Public Sub DoSomethingWithList(element as DataElement)
> >   dim list as List(of DataElement = element.LoadFullList()
> > End Sub
> >
> > Because element.LoadFullList() returns list(of Aor) it cannot be converted
> > to List(of DataElement).
> >
> > "Kevin Spencer" wrote:
> >
> >> Hi Paul,
> >>
> >> Since Aor is derived from DataElement, it certainly would be able to
> >> return
> >> a List(of Aor). It could return a list of any type that inherits
> >> DataElement.
> >>
> >> --
> >> HTH,
> >>
> >> Kevin Spencer
> >> Microsoft MVP
> >> ..Net Developer
> >> A watched clock never boils.
> >>
> >> "Paul" <P***@discussions.microsoft.com> wrote in message
> >> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
> >> >   I have a base class called DataElement.  Then I have several classes
> >> > that
> >> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each of
> >> > these
> >> > classes that inherit from DataElement have a Shared Function and an
> >> > instance
> >> > method that returns a List(of Aor) or List(of Aor0), etc., see below
> >> > for
> >> > basic class structures.
> >> >
> >> > Public Class DataElement
> >> > End Class
> >> >
> >> > Public Class Aor
> >> > Inherits DataElement
> >> >
> >> >   Public Function LoadFullList() as List(of Aor)
> >> >      Return GetFullList()
> >> >   End Function
> >> >
> >> >   Public Shared Function GetFullList() as List(of Aor)
> >> >   End Function
> >> >
> >> > End Class
> >> >
> >> > Then someplace else in the my application I have a screen that works
> >> > with
> >> > DataElements and needs to call the GetFullList or LoadFullList and I
> >> > can't
> >> > figure out a way to accomplish this.  I could put the LoadFullList
> >> > method
> >> > into the DataElement class, but then the return type would have to be
> >> > List(of
> >> > DataElement) and then I wouldn't be able to handle the returned list in
> >> > the
> >> > method that I want because it wouldn't be List(of Aor).
> >> >
> >> > Can someone help me out here.
> >>
> >>
> >>
>
>
>

"Kevin Spencer" wrote:

> Hi Paul,
>
> Forgive me for not recognizing the Generic syntax in your posts. I haven't
> delved into the VB.Net Generic syntax until now. Now that I understand your
> dilemma fully, I think I can help you resolve your issue.
>
> If you want to take full advantage of Generics, you need not create a base
> class and a number of inherited classes. You can define a single class with
> Generic  methods that takes type parameters. Example:
>
> Public Class DataElement
>
>   Public Function LoadFullList (Of ListType) ( ) as ListType
>      Return GetFullList (Of ListType) ( )
>   End Function
>
>   Public Shared Function GetFullList() (Of ListType)  as ListType
>   End Function
>
> End Class
>
> The class is not Generic, but both methods are. You can then call either
> method, passing the type of return value that you want from it, and it will
> return that type.
>
> I'm still not sure I'm understanding your question fully, though. Let me
> know if I've missed something.
>
> --
> HTH,
>
> Kevin Spencer
> Microsoft MVP
> ..Net Developer
> A watched clock never boils.
>
> "Paul" <P***@discussions.microsoft.com> wrote in message
> news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
> > The is not what my problem is.  My problem in that I have wanother
> > procedure
> > that is trying to deal with this list, but it is trying to do it at a
> > dataelement level
> >
> > Public Sub DoSomethingWithList(element as DataElement)
> >   dim list as List(of DataElement = element.LoadFullList()
> > End Sub
> >
> > Because element.LoadFullList() returns list(of Aor) it cannot be converted
> > to List(of DataElement).
> >
> > "Kevin Spencer" wrote:
> >
> >> Hi Paul,
> >>
> >> Since Aor is derived from DataElement, it certainly would be able to
> >> return
> >> a List(of Aor). It could return a list of any type that inherits
> >> DataElement.
> >>
> >> --
> >> HTH,
> >>
> >> Kevin Spencer
> >> Microsoft MVP
> >> ..Net Developer
> >> A watched clock never boils.
> >>
> >> "Paul" <P***@discussions.microsoft.com> wrote in message
> >> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
> >> >   I have a base class called DataElement.  Then I have several classes
> >> > that
> >> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each of
> >> > these
> >> > classes that inherit from DataElement have a Shared Function and an
> >> > instance
> >> > method that returns a List(of Aor) or List(of Aor0), etc., see below
> >> > for
> >> > basic class structures.
> >> >
> >> > Public Class DataElement
> >> > End Class
> >> >
> >> > Public Class Aor
> >> > Inherits DataElement
> >> >
> >> >   Public Function LoadFullList() as List(of Aor)
> >> >      Return GetFullList()
> >> >   End Function
> >> >
> >> >   Public Shared Function GetFullList() as List(of Aor)
> >> >   End Function
> >> >
> >> > End Class
> >> >
> >> > Then someplace else in the my application I have a screen that works
> >> > with
> >> > DataElements and needs to call the GetFullList or LoadFullList and I
> >> > can't
> >> > figure out a way to accomplish this.  I could put the LoadFullList
> >> > method
> >> > into the DataElement class, but then the return type would have to be
> >> > List(of
> >> > DataElement) and then I wouldn't be able to handle the returned list in
> >> > the
> >> > method that I want because it wouldn't be List(of Aor).
> >> >
> >> > Can someone help me out here.
> >>
> >>
> >>
>
>
>

"Paul" <P***@discussions.microsoft.com> wrote in message
news:661B101D-071E-41B0-85D9-E5C5691A7AB3@microsoft.com...
> OK I tried it and I'm still missing how I can do something.  Below is a
> simple example of the Class Structure that I have to test this out.  Just
> paste this onto a form a with a button and a textbox
>
> Public Class Form1
>
>    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
> System.EventArgs) Handles Button1.Click
>        Dim a As New Aor
>
>        DoSomething(a)
>
>        TextBox1.Text &= Microsoft.VisualBasic.ControlChars.CrLf
>        Dim list2 As List(Of Aor) = Aor.GetFullList(Of Aor)()
>        For Each a2 As Aor In list2
>            TextBox1.Text &= a2.ID & ", "
>        Next
>    End Sub
>
>    Public Sub DoSomething(ByVal element As DataElement)
>        Dim list As List(Of xxxxx) = element.LoadFullList(Of xxxxx)()
>        'The below works, but I don't know how to make the above work
>        'Dim list As List(Of Aor) = element.LoadFullList(Of Aor)()
>
>        For Each a2 As DataElement In list
>            TextBox1.Text &= a2.ID & ", "
>        Next
>    End Sub
> End Class
>
> Public Class DataElement
>
>    'bunch of code to provide base functionality for all my other classes
>    Private _ID As Int32
>    Public Property ID() As Int32
>        Get
>            Return _ID
>        End Get
>        Set(ByVal value As Int32)
>            _ID = value
>        End Set
>    End Property
>
>    Protected Shared Sub Load(ByVal row As System.Data.DataRow, ByVal
> element As DataElement)
>        Dim r As New Random
>        element.ID = r.Next
>    End Sub
>
>    Protected Shared Function Load(Of ListType As {DataElement, New})(ByVal
> ds As System.Data.DataSet) As List(Of ListType)
>        Dim list As New List(Of ListType)
>
>        'If ds IsNot Nothing AndAlso ds.Tables.Count > 0 Then
>        '    For Each row As System.Data.DataRow In ds.Tables(0).Rows
>        '        Dim element As DataElement = Me.Clone
>        '        DataElement.Load(row, element)
>        '        list.Add(element)
>        '    Next
>        'End If
>        For counter As Int32 = 0 To 5
>            Dim element As New ListType
>            DataElement.Load(ds.Tables(0).NewRow, element)
>            list.Add(element)
>        Next
>
>        Return list
>    End Function
>
>    Public Overridable Function LoadFullList(Of ListType As {DataElement,
> New})() As List(Of ListType)
>        Throw New NotImplementedException
>    End Function
> End Class
>
> Public Class Aor
>    Inherits DataElement
>
>    Public Overrides Function LoadFullList(Of ListType As {DataElement,
> New})() As List(Of ListType)
>        Return Aor.GetFullList(Of ListType)()
>    End Function
>
>    Public Shared Function GetFullList(Of ListType As {DataElement, New})()
> As List(Of ListType)
>        Dim list As New List(Of ListType)
>        Dim ds As New System.Data.DataSet
>        ds.Tables.Add(New System.Data.DataTable)
>        list = DataElement.Load(Of ListType)(ds)
>
>        Return list
>    End Function
> End Class
>
> "Kevin Spencer" wrote:
>
>> Hi Paul,
>>
>> Forgive me for not recognizing the Generic syntax in your posts. I
>> haven't
>> delved into the VB.Net Generic syntax until now. Now that I understand
>> your
>> dilemma fully, I think I can help you resolve your issue.
>>
>> If you want to take full advantage of Generics, you need not create a
>> base
>> class and a number of inherited classes. You can define a single class
>> with
>> Generic  methods that takes type parameters. Example:
>>
>> Public Class DataElement
>>
>>   Public Function LoadFullList (Of ListType) ( ) as ListType
>>      Return GetFullList (Of ListType) ( )
>>   End Function
>>
>>   Public Shared Function GetFullList() (Of ListType)  as ListType
>>   End Function
>>
>> End Class
>>
>> The class is not Generic, but both methods are. You can then call either
>> method, passing the type of return value that you want from it, and it
>> will
>> return that type.
>>
>> I'm still not sure I'm understanding your question fully, though. Let me
>> know if I've missed something.
>>
>> --
>> HTH,
>>
>> Kevin Spencer
>> Microsoft MVP
>> ..Net Developer
>> A watched clock never boils.
>>
>> "Paul" <P***@discussions.microsoft.com> wrote in message
>> news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
>> > The is not what my problem is.  My problem in that I have wanother
>> > procedure
>> > that is trying to deal with this list, but it is trying to do it at a
>> > dataelement level
>> >
>> > Public Sub DoSomethingWithList(element as DataElement)
>> >   dim list as List(of DataElement = element.LoadFullList()
>> > End Sub
>> >
>> > Because element.LoadFullList() returns list(of Aor) it cannot be
>> > converted
>> > to List(of DataElement).
>> >
>> > "Kevin Spencer" wrote:
>> >
>> >> Hi Paul,
>> >>
>> >> Since Aor is derived from DataElement, it certainly would be able to
>> >> return
>> >> a List(of Aor). It could return a list of any type that inherits
>> >> DataElement.
>> >>
>> >> --
>> >> HTH,
>> >>
>> >> Kevin Spencer
>> >> Microsoft MVP
>> >> ..Net Developer
>> >> A watched clock never boils.
>> >>
>> >> "Paul" <P***@discussions.microsoft.com> wrote in message
>> >> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
>> >> >   I have a base class called DataElement.  Then I have several
>> >> > classes
>> >> > that
>> >> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each
>> >> > of
>> >> > these
>> >> > classes that inherit from DataElement have a Shared Function and an
>> >> > instance
>> >> > method that returns a List(of Aor) or List(of Aor0), etc., see below
>> >> > for
>> >> > basic class structures.
>> >> >
>> >> > Public Class DataElement
>> >> > End Class
>> >> >
>> >> > Public Class Aor
>> >> > Inherits DataElement
>> >> >
>> >> >   Public Function LoadFullList() as List(of Aor)
>> >> >      Return GetFullList()
>> >> >   End Function
>> >> >
>> >> >   Public Shared Function GetFullList() as List(of Aor)
>> >> >   End Function
>> >> >
>> >> > End Class
>> >> >
>> >> > Then someplace else in the my application I have a screen that works
>> >> > with
>> >> > DataElements and needs to call the GetFullList or LoadFullList and I
>> >> > can't
>> >> > figure out a way to accomplish this.  I could put the LoadFullList
>> >> > method
>> >> > into the DataElement class, but then the return type would have to
>> >> > be
>> >> > List(of
>> >> > DataElement) and then I wouldn't be able to handle the returned list
>> >> > in
>> >> > the
>> >> > method that I want because it wouldn't be List(of Aor).
>> >> >
>> >> > Can someone help me out here.
>> >>
>> >>
>> >>
>>
>>
>>

"Kevin Spencer" wrote:

> Hi Paul,
>
> You're making me work too hard! I don't do VB.Net much these days! ;-)
>
> I'm a bit confused. The first thing I noticed is that you haven't declared a
> Generic class called "List(Of ListType)." But you're trying to use one.
> Would this be the System.Collections.Generic.List class?
>
> Also, I'm not entirely clear what you're trying to do here. This is, I
> think, the other thing that has had me stymied in my attempt to help you.
> Let me see if I can guess. You want a class that has a static (Shared)
> method to return a List of various types. But you want that class to return
> a List of whatever type that class happens to be. Am I right?
>
> If so, I see you're delving into Inheritance again, and that isn't
> necessary. Perhaps my type name confused you. Sounds like we've both been a
> bit confused! The tricky part, if I read your requirements right, is the
> static (Shared) function. A Shared class cannot be Generic, but a shared
> method can take a Generic parameter. So, you would need to declare both the
> class and the method to take type parameters, but they could not be the
> same, as the method is static (Shared). In other words, the method does not
> know what type an instance of the class is. So, you class definition would
> look more like the following:
>
> Public Class DataElement(Of T)
>
>     Public Function LoadFullList() _
>         As List(Of T)
>         Return GetFullList(Of T)()
>     End Function
>
>     Private Shared Function GetFullList(Of ListType)() _
>         As List(Of ListType)
>         Dim returnVal As New List(Of ListType)()
>         Return returnVal
>     End Function
>
>     Private Shared Function Load(Of ListType)( _
>         ByVal ds As DataSet) As List(Of DataElement(Of ListType))
>         Dim returnVal As List(Of DataElement(Of ListType))
>         returnVal = New List(Of DataElement(Of ListType))
>         For counter As Int32 = 0 To 5
>             Dim element As New DataElement(Of ListType)
>             element = CType(ds.Tables(0).Rows(0)(0), DataElement(Of
> ListType))
>             returnVal.Add(element)
>         Next
>         Return returnVal
>     End Function
>
> End Class
>
> Now, I don't know exactly where you're going with the first 2 functions.
> Obviously, to load a list from a DataSet, you need to reference the DataSet
> somewhere. The 3rd function takes one as a parameter, and will work fine as
> long as the data type in the Table Row is the type that is specified in the
> type parameter.
>
> But based on what you've given me so far in the area of requirements (which
> is nothing really), that's the best I can do. Hope it gets you on the right
> track. Time to take some naproxin sodium!
>
> --
> HTH,
>
> Kevin Spencer
> Microsoft MVP
> ..Net Developer
> A watched clock never boils.
>
>
> "Paul" <P***@discussions.microsoft.com> wrote in message
> news:661B101D-071E-41B0-85D9-E5C5691A7AB3@microsoft.com...
> > OK I tried it and I'm still missing how I can do something.  Below is a
> > simple example of the Class Structure that I have to test this out.  Just
> > paste this onto a form a with a button and a textbox
> >
> > Public Class Form1
> >
> >    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
> > System.EventArgs) Handles Button1.Click
> >        Dim a As New Aor
> >
> >        DoSomething(a)
> >
> >        TextBox1.Text &= Microsoft.VisualBasic.ControlChars.CrLf
> >        Dim list2 As List(Of Aor) = Aor.GetFullList(Of Aor)()
> >        For Each a2 As Aor In list2
> >            TextBox1.Text &= a2.ID & ", "
> >        Next
> >    End Sub
> >
> >    Public Sub DoSomething(ByVal element As DataElement)
> >        Dim list As List(Of xxxxx) = element.LoadFullList(Of xxxxx)()
> >        'The below works, but I don't know how to make the above work
> >        'Dim list As List(Of Aor) = element.LoadFullList(Of Aor)()
> >
> >        For Each a2 As DataElement In list
> >            TextBox1.Text &= a2.ID & ", "
> >        Next
> >    End Sub
> > End Class
> >
> > Public Class DataElement
> >
> >    'bunch of code to provide base functionality for all my other classes
> >    Private _ID As Int32
> >    Public Property ID() As Int32
> >        Get
> >            Return _ID
> >        End Get
> >        Set(ByVal value As Int32)
> >            _ID = value
> >        End Set
> >    End Property
> >
> >    Protected Shared Sub Load(ByVal row As System.Data.DataRow, ByVal
> > element As DataElement)
> >        Dim r As New Random
> >        element.ID = r.Next
> >    End Sub
> >
> >    Protected Shared Function Load(Of ListType As {DataElement, New})(ByVal
> > ds As System.Data.DataSet) As List(Of ListType)
> >        Dim list As New List(Of ListType)
> >
> >        'If ds IsNot Nothing AndAlso ds.Tables.Count > 0 Then
> >        '    For Each row As System.Data.DataRow In ds.Tables(0).Rows
> >        '        Dim element As DataElement = Me.Clone
> >        '        DataElement.Load(row, element)
> >        '        list.Add(element)
> >        '    Next
> >        'End If
> >        For counter As Int32 = 0 To 5
> >            Dim element As New ListType
> >            DataElement.Load(ds.Tables(0).NewRow, element)
> >            list.Add(element)
> >        Next
> >
> >        Return list
> >    End Function
> >
> >    Public Overridable Function LoadFullList(Of ListType As {DataElement,
> > New})() As List(Of ListType)
> >        Throw New NotImplementedException
> >    End Function
> > End Class
> >
> > Public Class Aor
> >    Inherits DataElement
> >
> >    Public Overrides Function LoadFullList(Of ListType As {DataElement,
> > New})() As List(Of ListType)
> >        Return Aor.GetFullList(Of ListType)()
> >    End Function
> >
> >    Public Shared Function GetFullList(Of ListType As {DataElement, New})()
> > As List(Of ListType)
> >        Dim list As New List(Of ListType)
> >        Dim ds As New System.Data.DataSet
> >        ds.Tables.Add(New System.Data.DataTable)
> >        list = DataElement.Load(Of ListType)(ds)
> >
> >        Return list
> >    End Function
> > End Class
> >
> > "Kevin Spencer" wrote:
> >
> >> Hi Paul,
> >>
> >> Forgive me for not recognizing the Generic syntax in your posts. I
> >> haven't
> >> delved into the VB.Net Generic syntax until now. Now that I understand
> >> your
> >> dilemma fully, I think I can help you resolve your issue.
> >>
> >> If you want to take full advantage of Generics, you need not create a
> >> base
> >> class and a number of inherited classes. You can define a single class
> >> with
> >> Generic  methods that takes type parameters. Example:
> >>
> >> Public Class DataElement
> >>
> >>   Public Function LoadFullList (Of ListType) ( ) as ListType
> >>      Return GetFullList (Of ListType) ( )
> >>   End Function
> >>
> >>   Public Shared Function GetFullList() (Of ListType)  as ListType
> >>   End Function
> >>
> >> End Class
> >>
> >> The class is not Generic, but both methods are. You can then call either
> >> method, passing the type of return value that you want from it, and it
> >> will
> >> return that type.
> >>
> >> I'm still not sure I'm understanding your question fully, though. Let me
> >> know if I've missed something.
> >>
> >> --
> >> HTH,
> >>
> >> Kevin Spencer
> >> Microsoft MVP
> >> ..Net Developer
> >> A watched clock never boils.
> >>
> >> "Paul" <P***@discussions.microsoft.com> wrote in message
> >> news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
> >> > The is not what my problem is.  My problem in that I have wanother
> >> > procedure
> >> > that is trying to deal with this list, but it is trying to do it at a
> >> > dataelement level
> >> >
> >> > Public Sub DoSomethingWithList(element as DataElement)
> >> >   dim list as List(of DataElement = element.LoadFullList()
> >> > End Sub
> >> >
> >> > Because element.LoadFullList() returns list(of Aor) it cannot be
> >> > converted
> >> > to List(of DataElement).
> >> >
> >> > "Kevin Spencer" wrote:
> >> >
> >> >> Hi Paul,
> >> >>
> >> >> Since Aor is derived from DataElement, it certainly would be able to
> >> >> return
> >> >> a List(of Aor). It could return a list of any type that inherits
> >> >> DataElement.
> >> >>
> >> >> --
> >> >> HTH,
> >> >>
> >> >> Kevin Spencer
> >> >> Microsoft MVP
> >> >> ..Net Developer
> >> >> A watched clock never boils.
> >> >>
> >> >> "Paul" <P***@discussions.microsoft.com> wrote in message
> >> >> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
> >> >> >   I have a base class called DataElement.  Then I have several
> >> >> > classes
> >> >> > that
> >> >> > inherit from this class, such as Aor, Aor0, plus a bunch more.  Each
> >> >> > of
> >> >> > these
> >> >> > classes that inherit from DataElement have a Shared Function and an
> >> >> > instance
> >> >> > method that returns a List(of Aor) or List(of Aor0), etc., see below
> >> >> > for
> >> >> > basic class structures.
> >> >> >
> >> >> > Public Class DataElement
> >> >> > End Class
> >> >> >
> >> >> > Public Class Aor
> >> >> > Inherits DataElement
> >> >> >
> >> >> >   Public Function LoadFullList() as List(of Aor)
> >> >> >      Return GetFullList()
> >> >> >   End Function
> >> >> >
> >> >> >   Public Shared Function GetFullList() as List(of Aor)
> >> >> >   End Function
> >> >> >
> >> >> > End Class
> >> >> >
> >> >> > Then someplace else in the my application I have a screen that works
> >> >> > with
> >> >> > DataElements and needs to call the GetFullList or LoadFullList and I
> >> >> > can't
> >> >> > figure out a way to accomplish this.  I could put the LoadFullList
> >> >> > method
> >> >> > into the DataElement class, but then the return type would have to
> >> >> > be
> >> >> > List(of
> >> >> > DataElement) and then I wouldn't be able to handle the returned list
> >> >> > in
> >> >> > the
> >> >> > method that I want because it wouldn't be List(of Aor).
> >> >> >
> >> >> > Can someone help me out here.
> >> >>
> >> >>
> >> >>
> >>
> >>
> >>
>
>
>

"Paul" <P***@discussions.microsoft.com> wrote in message
news:D58F94A7-CD11-4FE1-98B2-56732943FD21@microsoft.com...
> Sorry for the confusion, yes I'm using the Generic List
>
> You keep saying that I don't need inheritance, but I do.  What I have is a
> Base class called DataElement, which has a bunch of code to do different
> things for me automatically.  Then I have a lot of classes that inherit
> from
> this and actual concrete implementations adding the rest of the stuff that
> is
> needed for that specific class, such as various properties and other
> stuff.
>
> Then I have a method outside of the DataElement and the Aor class that
> deals
> with DataElements and needs to load a list of them, which is what was in
> the
> button click event of my example.  In this method I'm being passed a
> DataElement, but I don't know which type.  From this DataElement I need be
> able to load a list of this all of the elements and this is where I have
> the
> problem because I need to create a list, but I do not know the type of the
> list until runtime.
>
> "Kevin Spencer" wrote:
>
>> Hi Paul,
>>
>> You're making me work too hard! I don't do VB.Net much these days! ;-)
>>
>> I'm a bit confused. The first thing I noticed is that you haven't
>> declared a
>> Generic class called "List(Of ListType)." But you're trying to use one.
>> Would this be the System.Collections.Generic.List class?
>>
>> Also, I'm not entirely clear what you're trying to do here. This is, I
>> think, the other thing that has had me stymied in my attempt to help you.
>> Let me see if I can guess. You want a class that has a static (Shared)
>> method to return a List of various types. But you want that class to
>> return
>> a List of whatever type that class happens to be. Am I right?
>>
>> If so, I see you're delving into Inheritance again, and that isn't
>> necessary. Perhaps my type name confused you. Sounds like we've both been
>> a
>> bit confused! The tricky part, if I read your requirements right, is the
>> static (Shared) function. A Shared class cannot be Generic, but a shared
>> method can take a Generic parameter. So, you would need to declare both
>> the
>> class and the method to take type parameters, but they could not be the
>> same, as the method is static (Shared). In other words, the method does
>> not
>> know what type an instance of the class is. So, you class definition
>> would
>> look more like the following:
>>
>> Public Class DataElement(Of T)
>>
>>     Public Function LoadFullList() _
>>         As List(Of T)
>>         Return GetFullList(Of T)()
>>     End Function
>>
>>     Private Shared Function GetFullList(Of ListType)() _
>>         As List(Of ListType)
>>         Dim returnVal As New List(Of ListType)()
>>         Return returnVal
>>     End Function
>>
>>     Private Shared Function Load(Of ListType)( _
>>         ByVal ds As DataSet) As List(Of DataElement(Of ListType))
>>         Dim returnVal As List(Of DataElement(Of ListType))
>>         returnVal = New List(Of DataElement(Of ListType))
>>         For counter As Int32 = 0 To 5
>>             Dim element As New DataElement(Of ListType)
>>             element = CType(ds.Tables(0).Rows(0)(0), DataElement(Of
>> ListType))
>>             returnVal.Add(element)
>>         Next
>>         Return returnVal
>>     End Function
>>
>> End Class
>>
>> Now, I don't know exactly where you're going with the first 2 functions.
>> Obviously, to load a list from a DataSet, you need to reference the
>> DataSet
>> somewhere. The 3rd function takes one as a parameter, and will work fine
>> as
>> long as the data type in the Table Row is the type that is specified in
>> the
>> type parameter.
>>
>> But based on what you've given me so far in the area of requirements
>> (which
>> is nothing really), that's the best I can do. Hope it gets you on the
>> right
>> track. Time to take some naproxin sodium!
>>
>> --
>> HTH,
>>
>> Kevin Spencer
>> Microsoft MVP
>> ..Net Developer
>> A watched clock never boils.
>>
>>
>> "Paul" <P***@discussions.microsoft.com> wrote in message
>> news:661B101D-071E-41B0-85D9-E5C5691A7AB3@microsoft.com...
>> > OK I tried it and I'm still missing how I can do something.  Below is a
>> > simple example of the Class Structure that I have to test this out.
>> > Just
>> > paste this onto a form a with a button and a textbox
>> >
>> > Public Class Form1
>> >
>> >    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
>> > System.EventArgs) Handles Button1.Click
>> >        Dim a As New Aor
>> >
>> >        DoSomething(a)
>> >
>> >        TextBox1.Text &= Microsoft.VisualBasic.ControlChars.CrLf
>> >        Dim list2 As List(Of Aor) = Aor.GetFullList(Of Aor)()
>> >        For Each a2 As Aor In list2
>> >            TextBox1.Text &= a2.ID & ", "
>> >        Next
>> >    End Sub
>> >
>> >    Public Sub DoSomething(ByVal element As DataElement)
>> >        Dim list As List(Of xxxxx) = element.LoadFullList(Of xxxxx)()
>> >        'The below works, but I don't know how to make the above work
>> >        'Dim list As List(Of Aor) = element.LoadFullList(Of Aor)()
>> >
>> >        For Each a2 As DataElement In list
>> >            TextBox1.Text &= a2.ID & ", "
>> >        Next
>> >    End Sub
>> > End Class
>> >
>> > Public Class DataElement
>> >
>> >    'bunch of code to provide base functionality for all my other
>> > classes
>> >    Private _ID As Int32
>> >    Public Property ID() As Int32
>> >        Get
>> >            Return _ID
>> >        End Get
>> >        Set(ByVal value As Int32)
>> >            _ID = value
>> >        End Set
>> >    End Property
>> >
>> >    Protected Shared Sub Load(ByVal row As System.Data.DataRow, ByVal
>> > element As DataElement)
>> >        Dim r As New Random
>> >        element.ID = r.Next
>> >    End Sub
>> >
>> >    Protected Shared Function Load(Of ListType As {DataElement,
>> > New})(ByVal
>> > ds As System.Data.DataSet) As List(Of ListType)
>> >        Dim list As New List(Of ListType)
>> >
>> >        'If ds IsNot Nothing AndAlso ds.Tables.Count > 0 Then
>> >        '    For Each row As System.Data.DataRow In ds.Tables(0).Rows
>> >        '        Dim element As DataElement = Me.Clone
>> >        '        DataElement.Load(row, element)
>> >        '        list.Add(element)
>> >        '    Next
>> >        'End If
>> >        For counter As Int32 = 0 To 5
>> >            Dim element As New ListType
>> >            DataElement.Load(ds.Tables(0).NewRow, element)
>> >            list.Add(element)
>> >        Next
>> >
>> >        Return list
>> >    End Function
>> >
>> >    Public Overridable Function LoadFullList(Of ListType As
>> > {DataElement,
>> > New})() As List(Of ListType)
>> >        Throw New NotImplementedException
>> >    End Function
>> > End Class
>> >
>> > Public Class Aor
>> >    Inherits DataElement
>> >
>> >    Public Overrides Function LoadFullList(Of ListType As {DataElement,
>> > New})() As List(Of ListType)
>> >        Return Aor.GetFullList(Of ListType)()
>> >    End Function
>> >
>> >    Public Shared Function GetFullList(Of ListType As {DataElement,
>> > New})()
>> > As List(Of ListType)
>> >        Dim list As New List(Of ListType)
>> >        Dim ds As New System.Data.DataSet
>> >        ds.Tables.Add(New System.Data.DataTable)
>> >        list = DataElement.Load(Of ListType)(ds)
>> >
>> >        Return list
>> >    End Function
>> > End Class
>> >
>> > "Kevin Spencer" wrote:
>> >
>> >> Hi Paul,
>> >>
>> >> Forgive me for not recognizing the Generic syntax in your posts. I
>> >> haven't
>> >> delved into the VB.Net Generic syntax until now. Now that I understand
>> >> your
>> >> dilemma fully, I think I can help you resolve your issue.
>> >>
>> >> If you want to take full advantage of Generics, you need not create a
>> >> base
>> >> class and a number of inherited classes. You can define a single class
>> >> with
>> >> Generic  methods that takes type parameters. Example:
>> >>
>> >> Public Class DataElement
>> >>
>> >>   Public Function LoadFullList (Of ListType) ( ) as ListType
>> >>      Return GetFullList (Of ListType) ( )
>> >>   End Function
>> >>
>> >>   Public Shared Function GetFullList() (Of ListType)  as ListType
>> >>   End Function
>> >>
>> >> End Class
>> >>
>> >> The class is not Generic, but both methods are. You can then call
>> >> either
>> >> method, passing the type of return value that you want from it, and it
>> >> will
>> >> return that type.
>> >>
>> >> I'm still not sure I'm understanding your question fully, though. Let
>> >> me
>> >> know if I've missed something.
>> >>
>> >> --
>> >> HTH,
>> >>
>> >> Kevin Spencer
>> >> Microsoft MVP
>> >> ..Net Developer
>> >> A watched clock never boils.
>> >>
>> >> "Paul" <P***@discussions.microsoft.com> wrote in message
>> >> news:01F83058-71A7-424B-80F5-D2C3BA02BF03@microsoft.com...
>> >> > The is not what my problem is.  My problem in that I have wanother
>> >> > procedure
>> >> > that is trying to deal with this list, but it is trying to do it at
>> >> > a
>> >> > dataelement level
>> >> >
>> >> > Public Sub DoSomethingWithList(element as DataElement)
>> >> >   dim list as List(of DataElement = element.LoadFullList()
>> >> > End Sub
>> >> >
>> >> > Because element.LoadFullList() returns list(of Aor) it cannot be
>> >> > converted
>> >> > to List(of DataElement).
>> >> >
>> >> > "Kevin Spencer" wrote:
>> >> >
>> >> >> Hi Paul,
>> >> >>
>> >> >> Since Aor is derived from DataElement, it certainly would be able
>> >> >> to
>> >> >> return
>> >> >> a List(of Aor). It could return a list of any type that inherits
>> >> >> DataElement.
>> >> >>
>> >> >> --
>> >> >> HTH,
>> >> >>
>> >> >> Kevin Spencer
>> >> >> Microsoft MVP
>> >> >> ..Net Developer
>> >> >> A watched clock never boils.
>> >> >>
>> >> >> "Paul" <P***@discussions.microsoft.com> wrote in message
>> >> >> news:E8D361E2-DF9E-438E-8509-202ED82D1324@microsoft.com...
>> >> >> >   I have a base class called DataElement.  Then I have several
>> >> >> > classes
>> >> >> > that
>> >> >> > inherit from this class, such as Aor, Aor0, plus a bunch more.
>> >> >> > Each
>> >> >> > of
>> >> >> > these
>> >> >> > classes that inherit from DataElement have a Shared Function and
>> >> >> > an
>> >> >> > instance
>> >> >> > method that returns a List(of Aor) or List(of Aor0), etc., see
>> >> >> > below
>> >> >> > for
>> >> >> > basic class structures.
>> >> >> >
>> >> >> > Public Class DataElement
>> >> >> > End Class
>> >> >> >
>> >> >> > Public Class Aor
>> >> >> > Inherits DataElement
>> >> >> >
>> >> >> >   Public Function LoadFullList() as List(of Aor)
>> >> >> >      Return GetFullList()
>> >> >> >   End Function
>> >> >> >
>> >> >> >   Public Shared Function GetFullList() as List(of Aor)
>> >> >> >   End Function
>> >> >> >
>> >> >> > End Class
>> >> >> >
>> >> >> > Then someplace else in the my application I have a screen that
>> >> >> > works
>> >> >> > with
>> >> >> > DataElements and needs to call the GetFullList or LoadFullList
>> >> >> > and I
>> >> >> > can't
>> >> >> > figure out a way to accomplish this.  I could put the
>> >> >> > LoadFullList
>> >> >> > method
>> >> >> > into the DataElement class, but then the return type would have
>> >> >> > to
>> >> >> > be
>> >> >> > List(of
>> >> >> > DataElement) and then I wouldn't be able to handle the returned
>> >> >> > list
>> >> >> > in
>> >> >> > the
>> >> >> > method that I want because it wouldn't be List(of Aor).
>> >> >> >
>> >> >> > Can someone help me out here.
>> >> >>
>> >> >>
>> >> >>
>> >>
>> >>
>> >>
>>
>>
>>