Are nested functions possible in VBA?

Question

I'm trying to clean up code by stripping parameters from a function within a private scope, like this:

Function complicatedFunction(x as Double, param1 as Double, param2 as Double)
    ...
End Function

Function mainActionHappensHere(L as Double, U as Double ...)
    Function cleaner(x)
        cleaner = complicatedFunction(x, L, U)
    End Function
    ...
    cleaner(x)                       'Many calls to this function
    ...
End Function

Is this possible? Compiler complains, "Expected End Function", since I'm beginning a function before ending the outer one. And Google is no help :( PS I can't define cleaner() outside of mainActionHappensHere(), since then the correct L and U won't get passed into it.

Answer 1

VB.Net can do this, but I don't believe VBA can.

Two features that might help you simplify this code in other ways are overloaded functions or optional parameters. Here's an example using optional parameters:

Function complicatedFunction(x as Double, Optional param1 as Double = L, Optional param2 as Double = U) As Object
...
End Function

complicatedFunction(x)

However, L and U must be constants for this to work.

FWIW, and in case it turns out that you're really working with a VB.Net dialect, the VB.Net syntax looks like this:

Sub complicatedFunction(x as Double, param1 as Double, param2 as Double) 
    ...
End Sub

Function mainActionHappensHere(L as Double, U as Double ...)
    Dim cleaner As Func(Of Double, Object) = 
        Function(x) 
            Return complicatedFunction(x, L, U)
        End Function

    Dim y = cleaner(x)                       'Many calls to this function
    ...
End Function