Custom class varables & multi-threading

[CWITT]

I have a problem (so true..)

I have a program that uses several threads to get things done (simple enough).

However I recently discovered how to create my own class variables (*cheer*). So I decided to re-code my program to use these new variables (and thus cut huge chunks of extra code out). my problem is this.. I have a variable (Client) being "set" with a "new" statement inside a secondary thread (the cues to create it come from another computer via a port listener, and that part works fine), but when i try to access this variable outside the thread it responds as "nothing". this didn't happen before with basic variables (strings, Boolean, integers, etc) so I can only assume that I'm missing something really obvious in my class creation.

Can someone point me to the solution?

Namespace CardData
    Public Class Card
        Public Property Suit() As CardSuit
            Get
                Return m_Suit
            End Get
            Set
                m_Suit = Value
            End Set
        End Property
        Private m_Suit As CardSuit
        Public Property Value() As CardValue
            Get
                Return m_Value
            End Get
            Set
                m_Value = Value
            End Set
        End Property
        Private m_Value As CardValue
        Public Property Score() As Integer
            Get
                Return m_Score
            End Get
            Set
                m_Score = Value
            End Set
        End Property
        Private m_Score As Integer

        Public ReadOnly Property DisplayValue() As String
            Get
                Return Suit.ToString() + " " + Value.ToString()
            End Get
        End Property
    End Class

    Public Class Client
        Public Property PlayerHand() As List(Of Card)
            Get
                Return m_PlayerHand
            End Get
            Set
                If Value.Equals(m_PlayerHand) Then Return
                m_PlayerHand = Value
                If IsNothing(m_PlayerHand) Then Return
                PopulatePlayerCards()
            End Set
        End Property
        Private m_PlayerHand As New List(Of Card)
        Public Property PlayerSent() As List(Of Card)
            Get
                Return m_PlayerSent
            End Get
            Set
                m_PlayerSent = Value
            End Set
        End Property
        Private m_PlayerSent As New List(Of Card)
        Public Property HostHand() As Played
            Get
                Return m_HostHand
            End Get
            Set
                If Value.Equals(m_HostHand) Then Return
                m_HostHand = Value
                Client_Window.PopulateHostCards()
            End Set
        End Property
        Private m_HostHand As New Played
        Public Property Myturn As Boolean
            Get
                Return m_Myturn
            End Get
            Set
                m_Myturn = Value
            End Set
        End Property
        Private m_Myturn As Boolean = False
        Public Property IPlayed As Boolean
            Get
                Return m_IPlayed
            End Get
            Set
                m_IPlayed = Value
            End Set
        End Property
        Private m_IPlayed As Boolean = False
        Public Property Trade_Received As Boolean
            Get
                Return m_Trade_Received
            End Get
            Set
                m_Trade_Received = Value
            End Set
        End Property
        Private m_Trade_Received As Boolean = False

        Private Sub SortHand()
            Me.PlayerHand = PlayerHand.OrderBy(Function(x) x.Suit).ThenBy(Function(x) x.Value).ToList()
        End Sub

        Public Sub ShowHand()
            SortHand()
            For Each card In PlayerHand
                Debug.Print([Enum].GetName(GetType(CardSuit), card.Suit) + " " + [Enum].GetName(GetType(CardValue), card.Value) + "  ")
            Next
        End Sub
    End Class

    Public Class Played
        Public Property Type() As HandType
            Get
                Return m_Type
            End Get
            Set
                m_Type = Value
            End Set
        End Property
        Private m_Type As HandType
        Public Property Cards() As List(Of Card)
            Get
                Return m_Cards
            End Get
            Set
                m_Cards = Value
            End Set
        End Property
        Private m_Cards As List(Of Card)

        Sub New(Optional CardList As List(Of Card) = Nothing, Optional HType As HandType = Nothing)
            m_Type = HType
            m_Cards = CardList
        End Sub
    End Class
End Namespace

[Sitten Spynne]

I don't see any code regarding threads in what you posted. And there is no variable named 'Client'. There is a class named 'Client', but that is not a variable.

So I need to see more code before I can say anything.

But also beware this:

                Client_Window.PopulateHostCards()

There are two reasons this line makes me upset.

The first is Forms don't play well with multiple threads. If the secondary thread can set the HostHand property, you need to do a little bit of work to make sure you do Form-oriented work on the main thread.

The second is I don't see a variable named 'Client_Window', so I know you're using the default instance of the form. Default instances play ESPECIALLY poorly with threads. Basically every thread gets its own instance, so if this line got called from the secondary thread, a new Client_Window form will be made and you'll operate on THAT, and not the one on the screen.

[CWITT]

yes, that is the class i posted (that is used by the variable)

this is done is done inside a module (not the form)

Public GameData As CardData.Client

it gets "set" inside a thread (i'm not about to post the whole program) (located in the same module)

GameData = New CardData.Client

this part is in the "form"
but you can remove it. as i noted it runs fine, the issue comes later

Client_Window.PopulateHostCards()

my problem is after the thread is done. when i access "GameData", it's empty. = Nothing.

does that help?

[Sitten Spynne]

The best explanation I can come up with, since I can't see your code, is that you have declared a more local variable named GameData that hides the more global one. So you set the local variable but don't set the global one. Here's an example of what that looks like, and yes it's legal:

Module Module1

    Private GameData As GameData

    Sub Main()
        BadIdea()
        If GameData Is Nothing Then
            Console.WriteLine("Oh no!")
        End If
    End Sub

    Private Sub BadIdea()
        Dim GameData As GameData

        GameData = New GameData()
    End Sub

End Module

Public Class GameData

End Class

If that's the case, you can take some measures to not accidentally make the mistake again. Most VB developers follow special rules about how they capitalize their variables to help them understand if they're talking about something global, local, or a parameter. This makes it harder to accidentally access the wrong thing. Here's how I would have written the above:

Module Module1

    Private _gameData As GameData

    Sub Main()
        BadIdea()
        If _gameData Is Nothing Then
            Console.WriteLine("Oh no!")
        End If
    End Sub

    Private Sub BadIdea()
        Dim gameData As New GameData()
        _gameData = gameData
    End Sub

End Module

Public Class GameData

End Class

In the conventions I use, "_gameData" has an underscore in front to help me remember it's part of the Module. So if I want to touch the module's variable and I didn't type an underscore, I know I did wrong. When I declared the local data, I used the lowercase "gameData" to help me remember it's a variable, not the type. The type is capitalized "GameData" to help me remember that it's "important". This gets a little wonky because I also capitalize properties. Some people follow the rule, "Never name a property the same thing as a class". I find that I don't tend to get as confused about that as I do in the cases that make the underscore needed.

[CWITT]

It was a good theory (GameData being set in multiple locations), but it's only ever set (created) once.

I should clarify one thing (that may help). when i say GameData is empty when i try to access it after the thread runs that sets it, I am referring the the sub values. the GameData variable/object itself does contain all the sub variables, but they are all blank/empty/default states. this is why i think it's something i missed in the class creation code.. (OP), as the sub variables are all set and usable while in the thread. it's only when it exits the thread that they vanish.