Syntax options creating errors in VBA Macro for Excel - vba

Question

I'm having some trouble with syntax options while writing a VBA Macro for Excel. In VBA you can call a method on an object in two different ways:
foo.bar(arg1, arg2)
or
foo.bar arg1, arg2
I absolutely detest the second sort of syntax because I find it lacks any sort of clarity, so I normally adhere to the first option. However, I've come across a situation where using the first option creates an error, while the second executes fine. (This may perhaps be an indicator of other problems in my code.) Here is the culprit code:
Function GetFundList() As Collection
Dim newFund As FundValues
Range("A5").Select
Set GetFundList = New Collection
While Len(Selection.Value)
Set newFund = New FundValues
' I set the fields of newFund and move Selection
The problem is in this next line:
GetFundList.Add newFund
Wend
End Function
FundValues is a class I created that is essentially just a struct; it has three properties which get set during the loop.
Basically, when I call GetFundList.Add(newFund) I get the following error:
Run-time error '438':
Object doesn't support this property or method
But calling GetFundList.Add newFund is perfectly fine.
Does anyone understand the intricacies of VBA well enough to explain why this is happening?
EDIT: Thanks much for the explanations!

Answer 1

Adding items to a collection is not defined as a function returning a value, but as a sub routine:
Public Sub Add( _
ByVal Item As Object, _
Optional ByVal Key As String, _
Optional ByVal { Before | After } As Object = Nothing _
)
When calling another sub routine by name and sending arguments (without adding the "Call" statement), you are not required to add parentheses.
You need to add parentheses when you call a function that returns a value to a variable.
Example:
Sub Test_1()
Dim iCnt As Integer
Dim iCnt_B As Integer
Dim iResult As Integer
iCnt = 2
iCnt_B = 3
fTest_1 iCnt, iResult, iCnt_B
End Sub
Public Function fTest_1(iCnt, iResult, iCnt_B)
iResult = iCnt * 2 + iCnt_B * 2
End Function
Sub Test_2()
Dim iCnt As Integer
Dim iCnt_B As Integer
Dim iResult As Integer
iCnt = 2
iCnt_B = 3
iResult = fTest_2(iCnt, iCnt_B)
End Sub
Public Function fTest_2(iCnt, iCnt_B)
fTest_2 = iCnt * 2 + iCnt_B * 2
End Function
Let me know if not clear.

Answer 2

This Daily Dose of Excel conversation will be helpful.
When you use the parentheses you are forcing VBA to evaluate what's inside them and adding the result to the collection. Since NewFund has no default property - I assume - the evaluation yields nothing, so can't be added. Without the parentheses it evaluates to the instance of the class, which is what you want.
Another example. This:
Dim coll As Collection
Set coll = New Collection
coll.Add Range("A1")
Debug.Print coll(1); TypeName(coll(1))
and this ...
coll.Add (Range("A1"))
Debug.Print coll(1); TypeName(coll(1))
... both yield whatever is in A1 in the debug.window, because Value is Range's default property. However, the first will yield a type of "Range", whereas the type in the 2nd example is the data type in A1. In other words, the first adds a range to the collection, the 2nd the contents of the range.
On the other hand, this works:
Dim coll As Collection
Set coll = New Collection
coll.Add ActiveSheet
Debug.Print coll(1).Name
... and this doesn't:
coll.Add (ActiveSheet)
Debug.Print coll(1).Name
because ActiveSheet has no default property. You'll get an runtime error 438, just like in your question.

Answer 3

Here's another way of looking at the same thing.
Let assume that cell A1 contains the string Hi!
Function SomeFunc(item1, item2)
SomeFunc = 4
End Function
Sub Mac()
' here in both of the following two lines of code,
' item1 will be Variant/Object/Range, while item2 will be Variant/String:
SomeFunc Range("A1"), (Range("A1"))
Let i = SomeFunc(Range("A1"), (Range("A1")))
'this following is a compile syntax error
SomeFunc(Range("A1"), (Range("A1")))
' while here in both the following two lines of code,
' item1 will be Variant/String while item2 will be Variant/Object/Range:
SomeFunc ((Range("A1")), Range("A1")
Let j = SomeFunc((Range("A1")), Range("A1"))
'this following is a compile syntax error
SomeFunc((Range("A1")), Range("A1"))
Set r = Range("A1") ' sets r to Variant/Object/Range
Set r = (Range("A1")) ' runtime error 13, type mismatch; cannot SET r (as reference) to string "Hi!" -- Strings are not objects in VBA
Set r = Range("A1").Value ' runtime error (same)
Let r = Range("A1") ' set r to "Hi!" e.g. contents of A1 aka Range("A1").Value; conversion to value during let = assignment
Let r = (Range("A1")) ' set r to "Hi!" e.g. contents of A1 aka Range("A1").Value; conversion to value by extra ()'s
Let r = Range("A1").Value ' set r to "Hi!" by explicit use of .Value
End Sub
I only add this to help illustrate that there are two things going on here, which could be conflated.
The first is that the () in an expression that converts the item to its Value property as stated above in other answers.
The second is that functions invoked with intent to capture or use the return value require extra () surrounding the whole argument list, whereas functions (or sub's) invoked without intent to capture or use the return value (e.g. as statements) must be called without those same () surrounding the argument list. These surrounding () do not convert the argument list using .Value. When the argument list has only one parameter, this distinction can be particularly confusing.