VBScript: Passing Object to Function?

Question

The below example generates an error:

VBScript compilation error: Cannot use parentheses when calling a Sub

This error does not occur if all parameters are not objects.

Is there a special way to pass object parameters to VBScript functions?

Option Explicit

Dim obj

Function TestFunc(obj)
 WScript.Echo "Why doesn't this work?"
End Function

Set obj = CreateObject("Scripting.Dictionary")
obj.Add("key", "val")

TestFunc(obj) ' Error here!

Answer 1

This line

obj.Add("key", "val")

is causing the issue

change to

obj.Add "key", "val"

obj.Add is a sub which like the error says you can't use parens but your TestFunc is a function and can be called with parens

Answer 2

Only use parenthesis when you get a return value. Also use Sub instead of Function for functions that don't return something.

Answer 3

Parenthesis can only be used when..

1. You are calling a function that returns a value.
2. When the sub/function you are calling only takes 1 parameter.
3. If you precede the call with the Call keyword eg. Call TestFunc(obj)