I am Compiling My string Code(I read My Code from Text File) In vb and it works fine but i have a function that returns nullable double(Double?)
when i use it like this
Dim x As Double? = Myfunc(1000) 'it returns Nothing
my x variable fills with Nothing and it's ok
But When I use it like this
Dim x = Myfunc(1000) 'it returns Nothing
my x value is 0 !!!!
How can i solve this problem i want my users write codes like first code block
i tested all Option Explicit and Option Strict but it did not gain me anything.
please let me know how can i use Just dim x not Dim x as (type) thank you for your helps
UPDATE :this is Myfunc Code :
Function Myfunc(parameterId As Long) As Double?
If parameterId = 1000 Then
Return Nothing
Else
Return tot(parameterId) 'it is a dictionary of values
End If
End Function
And this Is my Compile Class :
Private Shared Function Compile(ByVal vbCode As String) As CompilerResults
Dim providerOptions = New Dictionary(Of String, String)
providerOptions.Add("CompilerVersion", "v4.0")
' Create the VB.NET compiler.
Dim vbProv = New VBCodeProvider(providerOptions)
' Create parameters to pass to the compiler.
Dim vbParams = New CompilerParameters()
' Add referenced assemblies.
vbParams.ReferencedAssemblies.Add("mscorlib.dll")
vbParams.ReferencedAssemblies.Add("System.Core.dll")
vbParams.ReferencedAssemblies.Add("System.dll")
vbParams.ReferencedAssemblies.Add("System.Windows.Forms.dll")
vbParams.ReferencedAssemblies.Add("System.Data.dll")
vbParams.ReferencedAssemblies.Add("Microsoft.VisualBasic.dll")
vbParams.ReferencedAssemblies.Add("System.Xml.dll")
vbParams.ReferencedAssemblies.Add("System.Xml.Linq.dll")
vbParams.GenerateExecutable = False
' Ensure we generate an assembly in memory and not as a physical file.
vbParams.GenerateInMemory = True
' Compile the code and get the compiler results (contains errors, etc.)
Return vbProv.CompileAssemblyFromSource(vbParams, vbCode)
End Function
As discussed above, Option Infer On needs to be included to force the compiler to create the variable as the required type - in this case the Double? returned by MyFunc.