Issue with converting in line recursive function from C# to VB .NET

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I have a function in C# I want to convert to vb. Never had much luck with inline functions in vb. The c# code is:

public Double CalculateMeanError(ImageBuffer target, Int32 parallelTaskCount = 4)
        {
            // checks parameters
            Guard.CheckNull(target, "target");

            // initializes the error
            Int64 totalError = 0;

            // prepares the function
            bool calculateMeanError(Pixel sourcePixel, Pixel targetPixel)
            {
                Color sourceColor = GetColorFromPixel(sourcePixel);
                Color targetColor = GetColorFromPixel(targetPixel);
                totalError += ColorModelHelper.GetColorEuclideanDistance(ColorModel.RedGreenBlue, sourceColor, targetColor);
                return false;
            }

            // performs the image scan, using a chosen method
            IList<Point> standardPath = new StandardPathProvider().GetPointPath(Width, Height);
            TransformPerPixel(target, standardPath, calculateMeanError, parallelTaskCount);

            // returns the calculates RMSD
            return Math.Sqrt(totalError/(3.0*Width*Height));
        }

What I have tried:

I tried several different code converters but it gets hung up on the inline recursive function calculateMeanError. I appreciate the help on inherit vs Implement. Here is the best vb code so far.

Public Function CalculateMeanError(ByVal target As ImageBuffer, Optional ByVal parallelTaskCount As Int32 = 4) As Double
    ' checks parameters
    Guard.CheckNull(target, "target")
    ' initializes the error
    Dim totalError As Int64 = 0
    ' prepares the function
    Dim calculateMeanError As Boolean
    Pixel
    sourcePixel
    Dim targetPixel As Pixel
    Dim sourceColor As Color = GetColorFromPixel(sourcePixel)
    Dim targetColor As Color = GetColorFromPixel(targetPixel)
    totalError = (totalError + ColorModelHelper.GetColorEuclideanDistance(ColorModel.RedGreenBlue, sourceColor, targetColor))
    Return false
    ' performs the image scan, using a chosen method
    Dim standardPath As IList(Of Point) = (New StandardPathProvider + GetPointPath(Width, Height))
    TransformPerPixel(target, standardPath, calculateMeanError, parallelTaskCount)
    ' returns the calculates RMSD
    Return Math.Sqrt((totalError / (3  _
                    * (Width * Height))))
End Function

Posted 4-Oct-19 0:38am

larry118

Updated 4-Oct-19 1:35am

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2 solutions

Solution 1

Try changing the name of the variable to something else. VB isn't case-sensitive, so the code converter might be confusing the internal var name with the function name.

Posted 4-Oct-19 1:31am

#realJSOP

Comments

larry118 4-Oct-19 10:42am

I tried both of these solutions, this is as close as I got.

Public Function CalculateMeanError(ByVal target As ImageBuffer, Optional ByVal parallelTaskCount As Int32 = 4) As Double
            ' checks parameters
            Guard.CheckNull(target, "target")
            ' initializes the error
            Dim totalError As Int64 = 0
            ' prepares the function

            Dim fn1 As Func(Of Pixel, Pixel, Boolean) = Function(ByVal sourcePixel As Pixel, ByVal targetPixel As Pixel)
                                                            Dim sourceColor As Color = GetColorFromPixel(sourcePixel)
                                                            Dim targetColor As Color = GetColorFromPixel(targetPixel)
                                                            totalError += ColorModelHelper.GetColorEuclideanDistance(ColorModel.RedGreenBlue, sourceColor, targetColor)
                                                            Return False
                                                        End Function

            Dim standardPath As IList(Of Point) = New StandardPathProvider().GetPointPath(Width, Height)
            TransformPerPixel(target, standardPath, fn1, parallelTaskCount)

            Return Math.Sqrt(totalError / (3.0 * Width * Height))
            Return False

        End Function<pre>

The error I get now is from the transformPerPixel(...,...,fn1,...) Says fn1 is value of type(Func(Of pixel,Pixel,Boolean) cannot be converted to ImageBuffer.transformPixelfunction.

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Richard Deeming · Accepted Answer · 2019-10-04T01:36:00

Try:

VB.NET

Public Function CalculateMeanError(ByVal target As ImageBuffer, Optional ByVal parallelTaskCount As Int32 = 4) As Double
    Guard.CheckNull(target, "target")
    
    Dim totalError As Int64 = 0
    
    Dim fn As Func(Of Pixel, Pixel, Boolean) = Function(sourcePixel As Pixel, targetPixel As Pixel)
        Dim sourceColor As Color = GetColorFromPixel(sourcePixel)
        Dim targetColor As Color = GetColorFromPixel(targetPixel)
        totalError += ColorModelHelper.GetColorEuclideanDistance(ColorModel.RedGreenBlue, sourceColor, targetColor)
        Return False
    End Function
    
    Dim standardPath As IList(Of Point) = New StandardPathProvider().GetPointPath(Width, Height)
    TransformPerPixel(target, standardPath, fn, parallelTaskCount)

    Return Math.Sqrt(totalError / (3.0 * Width * Height))
End Function

Lambda Expressions (Visual Basic) | Microsoft Docs[^]