"jayeldee" wrote:

> You probably want to change..
> Dim v as Vehicle = VehicleFactory.CreateVehicleInstance("Truck")
> to
> Dim t as Truck = VehicleFactory.CreateVehicleInstance("Truck")
> so you can access the Truck variables.
>
>

"GarrettD78" wrote:

> Accidently posted this to the wrong group so I am reposting.
> This is probably a newbie question but I am a little confused about how to go
> next with my code. I think I want to use a factory pattern in this situation
> but I am having trouble getting access to properties at the presentation
> level. So my situation is I have a Vehicle base class.
>
> Public Class Vehicle
>   Property BodyType as String
> End Class
>
> Then I have multiple inherited Classes
> Public Class Truck inherits Vehicle
>   Property Weight as String
> End Class
>
> Public Class Forklift inherits Vehicle
>   Property EngineType as String
> End Class
>
> My factory uses a select statement on the Body Type to decide which class to
> instantiate.
> Public Class VehicleFactory
>    Public Shared Function CreateVehicleInstance(bodyType as String) as Vehicle
>      Select Case bodyType
>                    Case "Truck"
>                         return v as New Truck
>                     Case "Forklift"
>                         return v as New Forklift
>     End Select
>          return v
>     End Function
> End Class
>
> My problems comes when I try return my class from the factory and access
> properties of the inherited class. The compiler won't let me compile it and I
> am not sure where to go. So for exampl
>
> Dim v as Vehicle = VehicleFactory.CreateVehicleInstance("Truck")
>
> v.Weight = 6 'this give me a compile error that Weight is not a member of 
> the base class
>
> I am trying to use this on the form and once the object is created then I
> need it accesible to the form to track whether it needs to be saved back to
> the database or not. Am I going about this all wrong?
>
>
>
> 
>

"rmacias" wrote:

> Can't you try something like:
>
> If TypeOf (v) Is Truck Then
>             CType(v, Truck).Weight = "6"
> End If
>
> "GarrettD78" wrote:
>
> > Accidently posted this to the wrong group so I am reposting.
> > This is probably a newbie question but I am a little confused about how to go
> > next with my code. I think I want to use a factory pattern in this situation
> > but I am having trouble getting access to properties at the presentation
> > level. So my situation is I have a Vehicle base class.
> >
> > Public Class Vehicle
> >   Property BodyType as String
> > End Class
> >
> > Then I have multiple inherited Classes
> > Public Class Truck inherits Vehicle
> >   Property Weight as String
> > End Class
> >
> > Public Class Forklift inherits Vehicle
> >   Property EngineType as String
> > End Class
> >
> > My factory uses a select statement on the Body Type to decide which class to
> > instantiate.
> > Public Class VehicleFactory
> >    Public Shared Function CreateVehicleInstance(bodyType as String) as Vehicle
> >      Select Case bodyType
> >                    Case "Truck"
> >                         return v as New Truck
> >                     Case "Forklift"
> >                         return v as New Forklift
> >     End Select
> >          return v
> >     End Function
> > End Class
> >
> > My problems comes when I try return my class from the factory and access
> > properties of the inherited class. The compiler won't let me compile it and I
> > am not sure where to go. So for exampl
> >
> > Dim v as Vehicle = VehicleFactory.CreateVehicleInstance("Truck")
> >
> > v.Weight = 6 'this give me a compile error that Weight is not a member of 
> > the base class
> >
> > I am trying to use this on the form and once the object is created then I
> > need it accesible to the form to track whether it needs to be saved back to
> > the database or not. Am I going about this all wrong?
> >
> >
> >
> > 
> >

"GarrettD78" wrote:

> I was hoping that someone might know how to to cast the type so I would have
> to do a switch statement everytime I had to deal with this object. I want to
> have a variable that is part of my form, that way once it is instantiated
> then I don't have to worry about the types. This is a big problem because the
> Truck is not the only vehicle that I will be dealing with. I think I am going
> about this wrong, but I can't figure out the right way to do it.
>
> I have a main form that they will enter the the vehicle information and then
> there will be other forms that build off the main one. I guess maybe how
> could I create an object when the user clicks the "Save" button and not let
> it get out of scope while the form is open. The only way I know to do this is
> to create a Private variable, but you have to give it a type and then I can
> instantiate it, but when the form loads I don't know the type. I guess I need
> to re-think this.
>
> "rmacias" wrote:
>
> > Can't you try something like:
> >
> > If TypeOf (v) Is Truck Then
> >             CType(v, Truck).Weight = "6"
> > End If
> >
> > "GarrettD78" wrote:
> >
> > > Accidently posted this to the wrong group so I am reposting.
> > > This is probably a newbie question but I am a little confused about how to go
> > > next with my code. I think I want to use a factory pattern in this situation
> > > but I am having trouble getting access to properties at the presentation
> > > level. So my situation is I have a Vehicle base class.
> > >
> > > Public Class Vehicle
> > >   Property BodyType as String
> > > End Class
> > >
> > > Then I have multiple inherited Classes
> > > Public Class Truck inherits Vehicle
> > >   Property Weight as String
> > > End Class
> > >
> > > Public Class Forklift inherits Vehicle
> > >   Property EngineType as String
> > > End Class
> > >
> > > My factory uses a select statement on the Body Type to decide which class to
> > > instantiate.
> > > Public Class VehicleFactory
> > >    Public Shared Function CreateVehicleInstance(bodyType as String) as Vehicle
> > >      Select Case bodyType
> > >                    Case "Truck"
> > >                         return v as New Truck
> > >                     Case "Forklift"
> > >                         return v as New Forklift
> > >     End Select
> > >          return v
> > >     End Function
> > > End Class
> > >
> > > My problems comes when I try return my class from the factory and access
> > > properties of the inherited class. The compiler won't let me compile it and I
> > > am not sure where to go. So for exampl
> > >
> > > Dim v as Vehicle = VehicleFactory.CreateVehicleInstance("Truck")
> > >
> > > v.Weight = 6 'this give me a compile error that Weight is not a member of 
> > > the base class
> > >
> > > I am trying to use this on the form and once the object is created then I
> > > need it accesible to the form to track whether it needs to be saved back to
> > > the database or not. Am I going about this all wrong?
> > >
> > >
> > >
> > > 
> > >

"rmacias" wrote:

> You can try something like this.  You can create a series of interfaces and
> abstract classes for your vehicles.  You can also then create an "instance"
> class that will hold your current instance of any vehicle created from the
> factory.  From there, you can pass it around to anyform you wish, and not
> have to worry about the type it is.
>
> The Below code is not throughly tested and is propably not the most ideal
> design, but it does get the point across and can perhaps serve as a starting
> point for you.  Modify it as you see fit:
>
> Public Interface IVehicle
>
>     ReadOnly Property BodyType() As String
>
> End Interface
>
> Public Interface ITruck
>
>     Property Weight() As String
>
> End Interface
>
> Public Interface IForklift
>
>     Property EngineType() As String
>
> End Interface
>
> Public MustInherit Class Vehicle
>     Implements IVehicle
>
>     Protected bodyT As String
>
>     Public Sub New()
>
>     End Sub
>
>     Public Sub New(ByVal bdyTp As String)
>         Me.bodyT = bdyTp
>     End Sub
>
>     Public ReadOnly Property BodyType() As String Implements IVehicle.BodyType
>         Get
>             Return Me.bodyT
>         End Get
>     End Property
>
> End Class
>
> Public Class Truck
>     Inherits Vehicle
>     Implements ITruck
>
>     Private wt As String
>
>
>     Public Sub New(ByVal bdyTp As String)
>         Me.bodyT = bdyTp
>     End Sub
>
>     Public Property Weight() As String Implements ITruck.Weight
>         Get
>             Return Me.wt
>         End Get
>         Set(ByVal Value As String)
>             'Validate that Value is a valid weight, if it is assign it
>             Me.wt = Value
>         End Set
>     End Property
>
> End Class
>
> Public Class Forklift
>     Inherits Vehicle
>     Implements IForklift
>
>     Private engineT As String
>
>     Public Sub New(ByVal bdyTp As String)
>         Me.bodyT = bdyTp
>     End Sub
>
>     Public Property EngineType() As String Implements IForklift.EngineType
>         Get
>             Return Me.engineT
>         End Get
>         Set(ByVal Value As String)
>             'Validate that Value is a valid EngineType
>             Me.engineT = Value
>         End Set
>     End Property
>
> End Class
>
> Public Class VehicleFactory
>
>     Public Shared Function CreateVehicle(ByVal bdyTyp As String) As Vehicle
>
>         Dim asm As [Assembly]
>         Dim asmTypes() As Type
>
>         'Create an instance of the executing assembly
>         asm = [Assembly].GetExecutingAssembly()
>
>         'Get a list of types from the current executing assembly
>         asmTypes = asm.GetTypes()
>
>         Dim typeNamespace As String
>         Dim typeToLookFor As String
>
>         For Each currentType As Type In asmTypes
>
>             'Derive the namespace of the current type of the list
>             typeNamespace = currentType.Namespace
>
>             'Derive the fully qualified name of the type we are looking for
>             typeToLookFor = typeNamespace & "." & bdyTyp
>
>             'If the current type matches the type we are looking for, return
> an instance of it.
>             'The comparison is case sensitive
>             If String.Compare(typeToLookFor, currentType.FullName, False) =
> 0 Then
>                 'Create the parameters for the constructor
>                 Dim args() As Object = {bdyTyp}
>                 Return Activator.CreateInstance(currentType, args)
>             End If
>
>         Next
>
>         'If we get this far, the type we were looking was not found in the
> assembly
>         Throw New Exception("The type " & bdyTyp & " was not found in the
> assembly.")
>
>     End Function
>
> End Class
>
> Public Class VehicleInstance
>     Implements IVehicle, ITruck, IForklift
>
>     Private m_currentVehicle As Vehicle
>
>     Public Sub New(ByVal bdyT As String)
>
>         Me.m_currentVehicle = VehicleFactory.CreateVehicle(bdyT)
>
>     End Sub
>
>     Public Property EngineType() As String Implements IForklift.EngineType
>         Get
>             If TypeOf (Me.m_currentVehicle) Is Forklift Then
>                 Return CType(Me.m_currentVehicle, Forklift).EngineType
>             Else
>                 'Either return Nothing, Empty String, Or Throw Exception
>             End If
>         End Get
>         Set(ByVal Value As String)
>
>             If TypeOf (Me.m_currentVehicle) Is Forklift Then
>                 CType(Me.m_currentVehicle, Forklift).EngineType = Value
>             Else
>                 'Throw exception or something else
>             End If
>
>         End Set
>     End Property
>
>     Public Property Weight() As String Implements ITruck.Weight
>         Get
>             If TypeOf (Me.m_currentVehicle) Is Truck Then
>                 Return CType(Me.m_currentVehicle, Truck).Weight
>             Else
>                 'Either return Nothing, Empty String, Or Throw Exception
>             End If
>         End Get
>         Set(ByVal Value As String)
>             If TypeOf (Me.m_currentVehicle) Is Truck Then
>                 CType(Me.m_currentVehicle, Truck).Weight = Value
>             Else
>                 'Throw exception or something else
>             End If
>         End Set
>     End Property
>
>     Public ReadOnly Property BodyType() As String Implements IVehicle.BodyType
>         Get
>             Return Me.m_currentVehicle.BodyType
>         End Get
>     End Property
> End Class
>
>  Sub Main()
>
>         Dim v As New VehicleInstance("Truck")
>
>         v.Weight = 6
>
>  End Sub
>
> "GarrettD78" wrote:
>
> > I was hoping that someone might know how to to cast the type so I would have
> > to do a switch statement everytime I had to deal with this object. I want to
> > have a variable that is part of my form, that way once it is instantiated
> > then I don't have to worry about the types. This is a big problem because the
> > Truck is not the only vehicle that I will be dealing with. I think I am going
> > about this wrong, but I can't figure out the right way to do it.
> >
> > I have a main form that they will enter the the vehicle information and then
> > there will be other forms that build off the main one. I guess maybe how
> > could I create an object when the user clicks the "Save" button and not let
> > it get out of scope while the form is open. The only way I know to do this is
> > to create a Private variable, but you have to give it a type and then I can
> > instantiate it, but when the form loads I don't know the type. I guess I need
> > to re-think this.
> >
> > "rmacias" wrote:
> >
> > > Can't you try something like:
> > >
> > > If TypeOf (v) Is Truck Then
> > >             CType(v, Truck).Weight = "6"
> > > End If
> > >
> > > "GarrettD78" wrote:
> > >
> > > > Accidently posted this to the wrong group so I am reposting.
> > > > This is probably a newbie question but I am a little confused about how to go
> > > > next with my code. I think I want to use a factory pattern in this situation
> > > > but I am having trouble getting access to properties at the presentation
> > > > level. So my situation is I have a Vehicle base class.
> > > >
> > > > Public Class Vehicle
> > > >   Property BodyType as String
> > > > End Class
> > > >
> > > > Then I have multiple inherited Classes
> > > > Public Class Truck inherits Vehicle
> > > >   Property Weight as String
> > > > End Class
> > > >
> > > > Public Class Forklift inherits Vehicle
> > > >   Property EngineType as String
> > > > End Class
> > > >
> > > > My factory uses a select statement on the Body Type to decide which class to
> > > > instantiate.
> > > > Public Class VehicleFactory
> > > >    Public Shared Function CreateVehicleInstance(bodyType as String) as Vehicle
> > > >      Select Case bodyType
> > > >                    Case "Truck"
> > > >                         return v as New Truck
> > > >                     Case "Forklift"
> > > >                         return v as New Forklift
> > > >     End Select
> > > >          return v
> > > >     End Function
> > > > End Class
> > > >
> > > > My problems comes when I try return my class from the factory and access
> > > > properties of the inherited class. The compiler won't let me compile it and I
> > > > am not sure where to go. So for exampl
> > > >
> > > > Dim v as Vehicle = VehicleFactory.CreateVehicleInstance("Truck")
> > > >
> > > > v.Weight = 6 'this give me a compile error that Weight is not a member of 
> > > > the base class
> > > >
> > > > I am trying to use this on the form and once the object is created then I
> > > > need it accesible to the form to track whether it needs to be saved back to
> > > > the database or not. Am I going about this all wrong?
> > > >
> > > >
> > > >
> > > > 
> > > >