[RESOLVED] Access a list of attributes

[janneman]

Hi,

I need to access a list of attributes as follows.

I'm drawing a curve named "CurveName". With Curvename I need to access the curve color, the data symbol etc.
I tried this:

Dim cllCurveAtt as new cllCurveAtt

sub SetAtt
     cllCurveAtt.Add(CurveName, "Color.Red")
     ......
end sub

If I then want to refer to the curve color through cllCurveAtt(CurveName) I get an error because "Color.Red" is not a system color, it should be Color.Red without the quotes. But if I remove the quotes in the assignment THAT causes an error because since CurveName is a string, that color thing should also be convertable to a string. Catch 22.
How can I do this in another way?

Thanks,

Jan Didden

[gep13]

Hey,

What is cllCurveAtt, is that a Class that you have created?

Gary

[janneman]

No, sorry, my bad.

I did:

Dim cllCurveAtt as new Collection()

at the top of the module, immediately after the class declaration.

Jan Didden

[gep13]

Hey,

Can you provide details of what exactly you are trying to achieve?

It sounds like what you actually want is a Generic Dictionary that holds both a Key and a Value.

http://msdn.microsoft.com/en-us/library/xfhwa508.aspx

Gary

[janneman]

Ok. I need to draw a bunch of curves. Each curve is identified by a string CurveName which I read from a file.

Each different CurveName has a number of associated attributes like the CurveColor, the CurveSymbol etc.

The curve drawing routine (which works ok) needs these attributes passed to it, and until now I just passed the parameters verbose everytime I call the sub. But I want to be able to have a central place where I have all the curve attributes in a kind of table and access them from there, so that I can call the curve drawing sub like:

call CurveDraw(CurveName, CurveName.Color, CurveName.Symbol)

Or just call it with CurveDraw(CurveName) and figure the attributes out locally.

Hope I'm halfway clear.

Jan Didden

[janneman]

After some more reading, I'll try this:

Public Class Curve
    Public Structure stcCurve
        Dim CurveName As String
        Dim CurveColor As Color
        Dim CurveSymbol As SymbolType
        Dim CurvePoints As PointPairList
    End Structure
End Class

Does that make sense?

Jan Didden

[gep13]

Hey,

Sorry, was having lunch

Yes, I would say in your case, a structure, or even it's own class with properties would make sense.

Gary

[janneman]

Hi Gary, hope it was a good lunch

So now I have this structure:

Public Structure stcCurve
Dim CurveName As String
Dim CurveColor As Color
Dim CurveSymbol As SymbolType
Dim CurvePoints As PointPairList
End Structure


When setting up the curve I say:

Dim ThisCurveInstance as new stcCurve , right.

Now how do I access that particular instance of stcCurve with the CurveName string I have?
And since each curve has it's own set of attributes in its own set of stcCurve, how do I set up these sets?

I'm sure it sound pretty silly but I just don't see through it.

Jan Didden

[gep13]

Hey,

Yes, it was very tasty thanks

Thinking about it, I would be inclined to do something like this:

Public Class stcCurve

    Private _curveName As String
    Public Property CurveName() As String
        Get
            Return _curveName
        End Get
        Set(ByVal value As String)
            _curveName = value
        End Set
    End Property


    Private _curveColor As Color
    Public Property CurveColor() As Color
        Get
            Return _curveColor
        End Get
        Set(ByVal value As Color)
            _curveColor = value
        End Set
    End Property


    Private _curveSymbol As SymbolType
    Public Property CurveSymbol() As SymbolType
        Get
            Return _curveSymbol
        End Get
        Set(ByVal value As SymbolType)
            _curveSymbol = value
        End Set
    End Property


    Private _curvePoints As PointPairList
    Public Property CurvePoints() As PointPairList
        Get
            Return _curvePoints
        End Get
        Set(ByVal value As PointPairList)
            _curvePoints = value
        End Set
    End Property
End Class

And then, you would use it like this:

        Dim curves As New List(Of stcCurve)

        Dim curve As New stcCurve
        curve.CurveColor = Color.AliceBlue
        curve.CurveName = "MyCurve"
        curve.SymbolType = blah
        curve.PointPairList = blah

        curves.Add(curve)

Here a Generic List of Type stcCurve is being used, which you can then add new instances of stcCurve to, and then you can enumerate through them when you need to using:

        For Each myCurve As stcCurve In curves
            MessageBox.Show(myCurve.CurveName)
        Next

Hope that makes sense!!

Gary

[janneman]

Hmmm. I *think* I get it.

If I then would want to pass the CurveColor to a sub based on the CurveName string, I would do like:

call DrawSub (Curvename, myCurve.CurveName.CurveColor) right?

Or just pass DrawSub(CurveName) and in the sub do:

TheColor = myCurve.CurveName.CurveColor OK?

I still am confused by the term 'instance'. If i create an instance of an object, is that then a completely independent one from any other same name object, or is it just to set a pointer to the earlier declaration? IOW, do instances of an object refer to one and the same object in memory?


Jan Didden

[gep13]

Hey,

Think of a class as a template, which all instances derive from. So in creating an instance of a class, you are creating a completely separate entity, that has all it's own properties, so we could do something like this:

        Dim curves As New List(Of stcCurve)

        Dim curve1 As New stcCurve
        curve1.CurveColor = Color.AliceBlue
        curve1.CurveName = "MyCurve2"
        curve1.SymbolType = blah1
        curve1.PointPairList = blah1

        Dim curve2 As New stcCurve
        curve2.CurveColor = Color.Red
        curve2.CurveName = "MyCurve2"
        curve2.SymbolType = blah2
        curve2.PointPairList = blah2

        curves.Add(curve1)
        curves.Add(curve2)

Here, curve1 and curve2 are two separate instances of the stcCurve class.

In terms of passing information about the instance of the stcCurve to a method, it depends on what you are doing in that method. If you need all of the information, you would simply do this:

DrawSub(curve1)
DrawSub(curve2)

You can't do what you are suggesting, as this would not be passing an instance of the class, but rather trying to pass the Type of the Object, which does not make sense.

Similarly, if you only needed to pass the CurveName of the stcCurve instance, you would do this:

DrawSub(curve1.CurveName)
DrawSub(curve2.CurveName)

Hope that makes sense!!

Gary

[janneman]

Thanks! That makes it much more clearer.

One remaining problem: when I try to access (in your example above) for example curve2.curvename from another module, it says "cannot access curve2 in this context because it is private", which is strange because I Dim'd curve2 directly under the class declaration as public, and I imported the namespaces in each module...

Jan Didden

[gep13]

Hey,

Can you post the code that you are using?

Gary

[janneman]

It's a lot of code, but this is the gist of it.

In Form1 I have:

Imports WindowsApplication1.FileStuff
Public Class bTest
    Dim Curves As New List(Of stcCurve)
    Dim Bias As New stcCurve
    Dim Temp As New stcCurve
    Dim Power As New stcCurve
    Dim BiasPoints = New PointPairList()
    Dim PowerPoints = New PointPairList()
   .......
   Public Sub SetUpCurves()
        Bias.CurveColor = Color.AliceBlue
        Bias.CurveName = "Bias Current"
        Bias.CurveSymbol = SymbolType.Circle
        Bias.CurvePoints = BiasPoints
        Curves.Add(Bias)

        Power.CurveColor = Color.AliceBlue
        Power.CurveName = "Power Dissipation"
        Power.CurveSymbol = SymbolType.Circle
        Power.CurvePoints = PowerPoints
        Curves.Add(Power)

        Temp.CurveColor = Color.AliceBlue
        Temp.CurveName = "Power Dissipation"
        Temp.CurveSymbol = SymbolType.Circle
        Temp.CurvePoints = PowerPoints
        Curves.Add(Temp)
    End Sub
   .....
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        'set up the graph
        'set curve attributes
        Call SetUpCurves()
        For Each myCurve As stcCurve In Curves
            MessageBox.Show(myCurve.CurveName)
        Next
    End Sub
End Class

... and that's fine.

Then in another module I have:

Imports WindowsApplication1.bTest
Public Class FileCSV
     ......
     Public Sub EnableCheckBox(ByVal CurveName As String)
                Select Case CurveName
                    Case bTest.Bias.CurveName 'this gives the error message
                        bTest.cbxRefIb.Enabled = True
                        bTest.cbxRefIb.Checked = False
                    Case bTest.Power.CurveName 'this gives the error message
                        bTest.cbxRefPc.Enabled = True
                        bTest.cbxRefPc.Checked = False
                    Case bTest.Temp.CurveName 'this gives the error message
                        bTest.cbxRefTc.Enabled = True
                        bTest.cbxRefTc.Checked = False
                End Select
            End Sub
        End Class

The error message is:

Error 2 'WindowsApplication1.bTest.Bias' is not accessible in this context because it is 'Private'.

[ForumAccount]

Dim = private. Change 'Dim' to 'Public'

[janneman]

Well yes I had tried that:

Public Class bTest
    Dim Curves As New List(Of stcCurve)
    Public Bias As New stcCurve
    Dim Temp As New stcCurve

... but that gives me:

Error 1 'Bias' cannot expose type 'CurveStuff.mdCurveStuff.stcCurve' outside the project through class 'bTest'.

I tried 'Shared' but that gives the same error as Dim.

Jan Didden

[ForumAccount]

Ok, and what are the modifiers of CurveStuff.mdCurveStuff.stcCurve?

[gep13]

Hey,

I think it would help as well if you told us exactly what you are trying to achieve. It may be the case that you don't need to use the approach you are currently using, but rather another solution may be available.

Gary

[janneman]

Ok, and what are the modifiers of CurveStuff.mdCurveStuff.stcCurve?

You mean this:

Namespace CurveStuff
    Module mdCurveStuff
        Public Class stcCurve

Jan Didden

[janneman]

Hi Gary,

The stuff you posted in #14 does exactly what I need: different curves that have different attributes, which I can pass to a sub that draws a curve on a Zedgraph pane.
I have all that stuff working but then I extended the nice single curve to the possibility to have a family of curves with different colors, shapes etc. As noted, your suggestion is very good.
The only remaining problem is with the access and visibility, and I guess I'll solve that as well with the pointers from you guys...

Jan Didden

[gep13]

Hey,

This might be a bit of an ask depending on the sensitivity of your project, but if you could upload a sample of the application as is, we might be able to find the problem sooner. Just a suggestion.

Gary

[janneman]

Gary,

I appreciate the offer to look at it, realizing you are giving freely of your time and expertise. I am a bit uncomfortable though with uploading the whole shebang, as I'm sure you can imagine.
Let me give it one more shot, after all this *should* be benign, no? ;-)
Then again, I might come back like the proverbial dog...

Jan Didden

[gep13]

Hey,

Nope, I totally understand.

Another suggestion would be to create another application, that uses the majority of functionality and that has the same issue, i.e. a streamlined version, that we could take a look at and make suggestions.

Gary

[ForumAccount]

You mean this:

Namespace CurveStuff
    Module mdCurveStuff
        Public Class stcCurve

Jan Didden

See, VS is telling you exactly what is wrong. You can't expose class stcCurve through a non-publicly declared Module.

Change your line:

Module mdCurveStuff

To:

Public Module mdCurveStuff

================================

I duplicated your error making assumptions on your code structure:

Namespace nmTest 
    Public Module mdTest 
        Public Class bTest 
            Public Bias As New CurveStuff.mdCurveStuff.stcCurve 'This will be underlined with that same error. 
        End Class 
    End Module 
End Namespace 
Namespace CurveStuff 
    Module mdCurveStuff 'I need to have the public modifier 
        Public Class stcCurve 
            Private _CurveName As String 
            Public Property CurveName() As String 
                Get 
                    Return _CurveName 
                End Get 
                Set(ByVal value As String) 
                    _CurveName = value 
                End Set 
            End Property 
        End Class 
    End Module 
End Namespace 
Namespace FileStuff 
    Public Class FileCSV 
        Dim bTest As New nmTest.mdTest.bTest 
        Public Sub ECB() 
            MsgBox(bTest.Bias.CurveName) 
        End Sub 
    End Class 
End Namespace

[janneman]

Yes!!

Declaring Bias public in the main module and then make the using module also public did it. I tried that, but only seperately.

You guys are awesome.

I programmed in assembly way down in 1974, a mil weapons system computer with (hold on) 8k 24 bit core mem. Did I tell you we kept a running score of free memory locations? Coming up with a changed multiply routine that saved another two locations was an achievement.
We had a major project in 1978 to quadruple mem to 32k. Man, we could program the world!

It was all so much simpler then. (Not really).

Jan Didden

[gep13]

Hey,

Glad to hear that you got it all working.

I missed all those fun times, didn't get into computers until about '99, still lots to learn!!

Remember to follow the links in my signature to close off your thread if all your questions have been answered.

Gary

[janneman]

Errr... Hmm... I'm not there yet.
So now that I have this collection of curves:

Public Class bTest
    Dim Curves As New List(Of stcCurve)
    Public Bias As New stcCurve
    Public Temp As New stcCurve
    Public Power As New stcCurve

Public Sub SetUpCurves()

        Bias.CurveColor = Color.AliceBlue
        Bias.CurveName = "Bias Current"
        Bias.CurveSymbol = SymbolType.Circle
        Bias.CurvePoints = BiasPoints
        Curves.Add(Bias)

        Power.CurveColor = Color.Red
        Power.CurveName = "Power Dissipation"
        Power.CurveSymbol = SymbolType.Square
        Power.CurvePoints = PowerPoints
        Curves.Add(Power)

        Temp.CurveColor = Color.Green
        Temp.CurveName = "Heatsink Temp"
        Temp.CurveSymbol = SymbolType.Diamond
        Temp.CurvePoints = TempPoints
        Curves.Add(Temp)

    End Sub

I have a string strDataType that holds the name of the curve whose attributes I want to access like "Bias" or "Power". So how do I access, say, the color of the Bias curve? I thought 'Curves.Bias.CurveColor' would be the way, and that I could somehow replace the 'Bias' in the pointer with the variable strDataType and use 'Curves.(strDataType).CurveColor' but that doesn't work.

What is the right way to do this (assuming there is a way...).

Jan Didden

[gep13]

Hey,

At the minute, you have a Generic Collection of stcCurve, which means you have the ability to index into that collection using something like this:

curves(1).CurveName

If however you want to identify the curve by a string literal, then you might want to think about using a Dictionary, something like this:

        Dim newCurves As New Dictionary(Of String, stcCurve)()

        newCurves.Add("test1", curve1)

        newCurves("test1").CurveName

You can use the Key, in this case test1, to grab the reference to the Curve in question.

Gary

[janneman]

I'll try that. I've the feeling I'm building a mini-database, but I'm learning, and that's great.

Jan

[janneman]

That does it. I have now for each curve the following:

        Power.CurveColor = Color.Red
        Power.CurveName = "Power Dissipation"
        Power.CurveSymbol = SymbolType.Square
        Power.CurvePoints = PowerPoints
        Curves.Add(Power)
        dicCurvesList.Add("Power", Curves(1))

And with the string strDataType that holds the name of the curve, I can indeed access for instance the color with

ThisColor = dicCurvesList(strDataType).CurveColor

Thanks! Exactly what I wanted. Everything in one place and easily extentable if necessary.
On to the next hurdle ;-)

Jan Didden

[gep13]

Good stuff!!! Glad to hear you got it to work the way that you wanted it to!!