VB ReDim of member field programmatically

Question

I am trying to ReDim a member array based on reading a file. I cannot figure out how to do it. This is what I tried, but it does not work.

Public Class BS
    Public A() As String
    Public B() As Double
    Public C() As Double
End Class

Public Class SB

    Public MyBS() As BS

    'ReadFieldString is a function that returns a string of the field name of Class BS,
    'i.e., A, B or C.  For test purpose, retun a constant
    Public Function ReadFieldString() As String
        Return "B"
    End Function

    'GetArrayDim is a function that returns an integer, which is the size of the array
    'of that field name. For test purpose, retun a constant
    Public Function GetArrayDim() As Integer
        Return 1
    End Function

    Public Sub DimArrays()
        ReDim MyBS(3)
        Dim i As Integer
        For i = 0 To MyBS.Length - 1
            'Try to ReDim the member of MyBS
            ReDim MyBS(i).GetType.GetField(ReadFieldString)(GetArrayDim)
        Next()
    End Sub

End Class

The ReDim statement has the error "Expression is a value and therefore cannot be the target of an assignment." Thanks in advance.

Answer 1

I'm not sure ReDim works like that. Changing the code to this will achieve what I believe you are after:

Public Sub DimArrays()
    ReDim MyBS(3)
    Dim i As Integer
    For i = 0 To MyBS.Length - 1
        MyBS(i) = New BS()
        Dim f = GetType(BS).GetField(ReadFieldString())
        f.SetValue(MyBS(i), Array.CreateInstance(f.FieldType.GetElementType(), GetArrayDim()))
    Next
End Sub

However, I think a better approach would be to specify the array size in the BS constructor.