VBA: evaluation order - vba

Question

when VBA executes this line:
GetClass1().Test(GetParam())
the GetParam function is evaluated before the GetClass1() call.
What is a good way to change this behaviour?
the only thing I came up with is this workaround:
With GetClass1
.Test(GetParam())
End With
here's the full example code, so that you can easily test it:
Class1
Option Explicit
Public Function Test(ByVal sText As String) As String
Debug.Print "Class1.Text: " & sText
Test = "Class1.Text: " & sText
End Function
Module1
Option Explicit
Private Function GetClass1() As Class1
Set GetClass1 = New Class1
Debug.Print "GetClass1()"
End Function
Private Function GetParam() As String
GetParam = "Param"
Debug.Print "GetParam()"
End Function
Private Sub Test()
Debug.Print "Test=" + GetClass1().Test(GetParam())
With GetClass1
Debug.Print "TestWith=" + .Test(GetParam())
End With
End Sub
Output when you run Test()
GetParam()
GetClass1()
Class1.Text: Param
Test=Class1.Text: Param
GetClass1()
GetParam()
Class1.Text: Param
TestWith=Class1.Text: Param

Answer 1

The evaluation order here is ok i think. The calling order of nested functions is from the inner most one to the outer most one which can't be done differently because outer most function needs to know its arguments and this arguments are evalueted only after the inner function was executed.
In your code (the first way) the object of type Class1 is created after the function GetParam() was called and this is because the object is created at the moment when function GetClass1() is called. In the second way with With GetClass1 the object is created immedialtelly after With and the call stack looks differently indeed.
What you can do is to create another class say 'Wrap' and this class will be responsible for creation of instance of type Class1.
E.g. like this:
' Class module Wrap
Private m_class1 As Class1
Public Function GetClass1() As Class1
Set GetClass1 = m_class1
Debug.Print "GetClass1()"
End Function
Private Sub Class_Initialize()
Set m_class1 = New Class1
End Sub
' Module code
Private Function GetParam() As String
GetParam = "Param"
Debug.Print "GetParam()"
End Function
Private Sub Test()
Dim wp As Wrap
Set wp = New Wrap
Debug.Print "Test=" + wp.GetClass1().Test(GetParam())
Debug.Print "---------------------------------------"
With New Wrap
Debug.Print "TestWith=" + .GetClass1.Test(GetParam())
End With
End Sub
Here the instance of class Class1 is created exactly at the moment you call New for class Wrap. So Set wp = New Wrap executes and creates the instance and the same way works With New Wrap, it executes and creates the instance as well.
But do not do it like this:
Dim wp As New Wrap
... then you will have the same behaviour like you had when the function GetClass1() was part of the Module1, which is: 'the instance is not created until it is needed' so you do not have the control of the moment of creation. HTH