I had a line of VBA code that basically looked like this:
MyControls.Add(Factory.CreateMyControl(param1, param2))
Where Factory.CreateMyControl is just a sneaky way to allow the new instance of my class module being returned to have a constructor.
It was working without any issues for several weeks. Suddenly, it begins throwing the error object doesn't support this property or method which is baffling me because everything looks like it always has.
After stepping into and through the code, I finally narrowed it down to the line above, and found the issue. The issue was the pair of parentheses surrounding the parameter(s) for the Add function. When I changed the code to the following:
MyControls.Add Factory.CreateMyControl(param1, param2)
It worked just as it always had before the unexpected break.
I now understand that this is the basic syntax in VBA for calling Sub's with parameters: to simply include all parameters in a comma-separated fashion without any parentheses (unless you're setting a Function's return value to another variable or using it's value for some other purpose).
My real question is, why did this suddenly just stop working?
Is it a common occurrence using VBA in Office 2007 for code that once worked to break without warning?
Or could this have been caused by some kind of patch that happened without my knowledge?
With parentheses around, the Sub's parameters per default were passed ByVal instead of ByRef. Without parentheses around, the default is ByRef
Example:
Dim r As Range
Sub test(v As Variant)
MsgBox TypeName(v)
End Sub
Sub main()
Set r = Range("A1")
test r 'ByRef; TypeName is Range
test (r) 'ByVal; TypeName is not Range but the type of the content of A1
End Sub
Related
I've not seen this in other languages but I see it a lot in VBA (which I just started working with). Suppose you have a table in Word and wish to set the rows to a certain height. If you do this
tbl.Rows.SetHeight InchesToPoints(1), wdRowHeightExactly
the table's rows indeed are set to 72 points or 1 inch in height. However, if you surround the arguments in parentheses, something I did instinctively, VBA gives an error -- expected:=.
I can solve this by using a throw-away variable, like this
x = tbl.Rows.SetHeight (InchesToPoints(1), wdRowHeightExactly)
or, of course, I can simply not surround the arguments in parentheses.
Microsoft's documentation on the SetHeight method doesn't mention any return value, but in any case, this behavior is extensive throughout VBA. It's not specific to the SetHeight method.
My questions: What is this called? Should I use a throw-away variable or throw away the parentheses? What's the logic from Microsoft's point of view? Are there consequences to using one or the other, consequences I can't imagine (because they are unknown unknowns)?
Definitely don't introduce a "throw-away variable", especially if it's not declared, and especially if what you're invoking is a Sub, a procedure that doesn't return any value. Well you can, if you don't mind a compile-time error:
Expected Function or variable.
Now...
this behavior is extensive throughout VBA. It's not specific to the SetHeight method.
#Yoe3k put it nicely:
As for what it is called, I would guess "correct syntax" is the most appropriate word.
That's the whole answer: it's not about SetHeight, it's about how VBA's implicit procedure/member call syntax works. The explicit Call syntax has been obsolete since the wonderful advent of implicit calls, about a quarter of a century ago. So splattering Call keywords left & right and all over your code will, indeed, keep you the parentheses... if you hold them so dear.
But the "logic" of the implicit call syntax isn't all that complicated, really.
What follows is what I wrote on Documentation.SO about VBA and parentheses, hope it helps.
This is confusing. Why not just always use parentheses?
Parentheses are used to enclose the arguments of function calls. Using them for procedure calls can cause unexpected problems.
Because they can introduce bugs, both at run-time by passing a possibly unintended value to the procedure, and at compile-time by simply being invalid syntax.
Run-time
Redundant parentheses can introduce bugs. Given a procedure that takes an object reference as a parameter...
Sub DoSomething(ByRef target As Range)
End Sub
...and called with parentheses:
DoSomething (Application.ActiveCell) 'raises an error at runtime
This will raise an "Object Required" runtime error #424. Other errors are possible in other circumstances: here the Application.ActiveCell Range object reference is being evaluated and passed by value regardless of the procedure's signature specifying that target would be passed ByRef. The actual value passed ByVal to DoSomething in the above snippet, is Application.ActiveCell.Value.
Parentheses force VBA to evaluate the value of the bracketed expression, and pass the result ByVal to the called procedure. When the type of the evaluated result mismatches the procedure's expected type and cannot be implicitly converted, a runtime error is raised.
Compile-time
This code will fail to compile:
MsgBox ("Invalid Code!", vbCritical)
Because the expression ("Invalid Code!", vbCritical) cannot be evaluated to a value.
This would compile and work:
MsgBox ("Invalid Code!"), (vbCritical)
But would definitely look silly. Avoid redundant parentheses.
The most serious consequence of using parentheses inappropriately can best be demonstrated by code such as:
Sub Test()
Dim r As Range
Set r = Range("A1")
TestSub r
TestSub (r)
End Sub
Sub TestSub(parm As Range)
MsgBox parm.Address
End Sub
In that code TestSub r correctly passes a range object to TestSub. However, placing parentheses around the r, i.e. TestSub (r) causes VBA to evaluate r using its Value property and is therefore equivalent to TestSub r.Value. This then gives an error as it is passing a Variant (maybe a Variant/Double with a value of 123.45) to a subroutine that is expecting a Range.
It is basically just incorrect syntax to enclose parameters to a Subroutine within parentheses. They should only be used when a Function is returning a value.
P.S. I apologise that my example is Excel VBA. I hadn't noticed that the question was Word VBA, plus I could knock up an Excel example quicker than I could research Word VBA enough to give an example in it. The principle is the same in both though.
I'm using Access VBA, and I keep getting
Compile error: Argument not optional
whenever I try to pass a collection into a function. What is going on?
Private Sub btnTest_Click()
Dim GarbageLanguages As New Collection
GarbageLanguages.Add "VBA"
PrintCollectionCount (GarbageLanguages) '<-- error happens here
End Sub
Public Sub PrintCollectionCount(c As Collection)
Debug.Print c.Count
End Sub
Short Answer
Remove the parentheses from the following line:
PrintCollectionCount (GarbageLanguages)
Long Answer
For better or worse (mostly worse), VBA has both functions and subroutines:
Function - expression that must return a value
Subroutine - statement that cannot return a value
Unfortunately, using each of them requires slightly different syntax. Suprisingly, this is not a valid subroutine call:
Subroutine(arguments)
Instead, you need to use one of these two options:
Call Subroutine(arguments)
Subroutine arguments
It's even more unfortunate that when you use the wrong syntax, all you get is extremely cryptic error messages. Finally, it's also hard to get used to not using parenthesis because single arguments that are primitive types instead of objects actually work fine:
Subroutine(SomeString) ' works
Subroutine(SomeInteger) ' works
Subroutine(SomeObject) ' does not work
Subroutine(SomeString, SomeInteger) ' does not work
Aside from memorizing the awful error messages, you can try to train yourself to look out for whenever a space gets automatically inserted after the subroutine's name. This:
Subroutine(argument)
gets changed to this:
Subroutine (argument) '<-- RED FLAG
I am learning how to create input boxes and I keep getting the same error. I have tried two different computers and have received the same error. The error I get is a "Compile Error: Wrong number of arguments or invalid property assignment"
Here is my code:
Option Explicit
Sub InputBox()
Dim ss As Worksheet
Dim Link As String
Set ss = Worksheets("ss")
Link = InputBox("give me some input")
ss.Range("A1").Value = Link
With ss
If Link <> "" Then
MsgBox Link
End If
End With
End Sub
When I run the code, it highlights the word "inputbox"
And help would be greatly appreciated.
Thanks,
G
Three things
1) Call your sub something other than the reserved word InputBox as this may confuse things. *Edit... and this alone will resolve your error. See quote from #Mat's Mug.
2) A̶p̶p̶l̶i̶c̶a̶t̶i̶o̶n̶.̶I̶n̶p̶u̶t̶B̶o̶x̶(̶"̶g̶i̶v̶e̶ ̶m̶e̶ ̶s̶o̶m̶e̶ ̶i̶n̶p̶u̶t̶"̶)̶ Use VBA.Interaction.InputBox("give me some input"). You can do this in addition to the first point. Documentation here.
3) Compare with vbNullString rather than "" . See here. Essentially, you will generally want to do this as vbNullString is, as described in that link, faster to assign and process and it takes less memory.
Sub GetInput()
Dim ss As Worksheet
Dim Link As String
Set ss = Worksheets("ss")
Link = VBA.Interaction.InputBox("give me some input")
ss.Range("A1").Value = Link
' With ss ''commented out as not sure how this was being used. It currently serves no purpose.
If Link <> vbNullString Then
MsgBox Link
End If
' End With
End Sub
EDIT: To quote #Mat's Mug:
[In the OP's code, what is actually being called is] VBA.Interaction.InputBox, but the call is shadowed by the procedure's identifier "InputBox", which is causing the error. Changing it to Application.InputBox "fixes" the problem, but doesn't invoke the same function at all. The solution is to either fully-qualify the call (i.e. VBA.Interaction.InputBox), or to rename the procedure (e.g. Sub DoSomething(), or both.
Sub InputBox()
That procedure is implicitly Public. Presumably being written in a standard module, that makes it globally scoped.
Link = InputBox("give me some input")
This means to invoke the VBA.Interaction.InputBox function, and would normally succeed. Except by naming your procedure InputBox, you've changed how VBA resolves this identifier: it no longer resolves to the global-scope VBA.Interaction.InputBox function; it resolves to your InputBox procedure, because VBAProject1.Module1.InputBox (assuming your VBA project and module name are respectively VBAProject1 and Module1) are always going to have priority over any other function defined in any other referenced type library - including the VBA standard library.
When VBA resolves member calls, it only looks at the identifier. If the parameters mismatch, it's not going to say "hmm ok then, not that one" and continue searching the global scope for more matches with a different signature - instead it blows up and says "I've found the procedure you're looking for, but I don't know what to do with these parameters".
If you change your signature to accept a String parameter, you get a recursive call:
Sub InputBox(ByVal msg As String)
That would compile and run... and soon blow up the call stack, because there's a hard limit on how deep the runtime call stack can go.
So one solution could be to properly qualify the InputBox call, so that the compiler knows exactly where to look for that member:
Link = VBA.Interaction.InputBox("give me some input")
Another solution could be to properly name your procedure so that its name starts with a verb, roughly describes what's going on, and doesn't collide with anything else in global scope:
Sub TestInputBox()
Another solution/work-around could be to use a similar function that happens to be available in the Excel object model, as QHarr suggested:
Link = Application.InputBox("give me some input")
This isn't the function you were calling before though, and that will only work in a VBA host that has an InputBox member on its Application class, whereas the VBA.Interaction.InputBox global function is defined in the VBA standard library and works in any VBA host.
A note about this:
If Link <> "" Then
This condition will be False, regardless of whether the user clicked OK or cancelled the dialog by "X-ing out". The InputBox function returns a null string pointer when it's cancelled, and an actual empty string when it's okayed with, well, an empty string input.
So if an empty string needs to be considered a valid input and you need to be able to tell it apart from a cancelled inputbox, you need to compare the string pointers:
If StrPtr(Link) <> 0 Then
This condition will only be False when the user explicitly cancelled, and will still evaluate to True if the user provided a legit empty string.
I've not seen this in other languages but I see it a lot in VBA (which I just started working with). Suppose you have a table in Word and wish to set the rows to a certain height. If you do this
tbl.Rows.SetHeight InchesToPoints(1), wdRowHeightExactly
the table's rows indeed are set to 72 points or 1 inch in height. However, if you surround the arguments in parentheses, something I did instinctively, VBA gives an error -- expected:=.
I can solve this by using a throw-away variable, like this
x = tbl.Rows.SetHeight (InchesToPoints(1), wdRowHeightExactly)
or, of course, I can simply not surround the arguments in parentheses.
Microsoft's documentation on the SetHeight method doesn't mention any return value, but in any case, this behavior is extensive throughout VBA. It's not specific to the SetHeight method.
My questions: What is this called? Should I use a throw-away variable or throw away the parentheses? What's the logic from Microsoft's point of view? Are there consequences to using one or the other, consequences I can't imagine (because they are unknown unknowns)?
Definitely don't introduce a "throw-away variable", especially if it's not declared, and especially if what you're invoking is a Sub, a procedure that doesn't return any value. Well you can, if you don't mind a compile-time error:
Expected Function or variable.
Now...
this behavior is extensive throughout VBA. It's not specific to the SetHeight method.
#Yoe3k put it nicely:
As for what it is called, I would guess "correct syntax" is the most appropriate word.
That's the whole answer: it's not about SetHeight, it's about how VBA's implicit procedure/member call syntax works. The explicit Call syntax has been obsolete since the wonderful advent of implicit calls, about a quarter of a century ago. So splattering Call keywords left & right and all over your code will, indeed, keep you the parentheses... if you hold them so dear.
But the "logic" of the implicit call syntax isn't all that complicated, really.
What follows is what I wrote on Documentation.SO about VBA and parentheses, hope it helps.
This is confusing. Why not just always use parentheses?
Parentheses are used to enclose the arguments of function calls. Using them for procedure calls can cause unexpected problems.
Because they can introduce bugs, both at run-time by passing a possibly unintended value to the procedure, and at compile-time by simply being invalid syntax.
Run-time
Redundant parentheses can introduce bugs. Given a procedure that takes an object reference as a parameter...
Sub DoSomething(ByRef target As Range)
End Sub
...and called with parentheses:
DoSomething (Application.ActiveCell) 'raises an error at runtime
This will raise an "Object Required" runtime error #424. Other errors are possible in other circumstances: here the Application.ActiveCell Range object reference is being evaluated and passed by value regardless of the procedure's signature specifying that target would be passed ByRef. The actual value passed ByVal to DoSomething in the above snippet, is Application.ActiveCell.Value.
Parentheses force VBA to evaluate the value of the bracketed expression, and pass the result ByVal to the called procedure. When the type of the evaluated result mismatches the procedure's expected type and cannot be implicitly converted, a runtime error is raised.
Compile-time
This code will fail to compile:
MsgBox ("Invalid Code!", vbCritical)
Because the expression ("Invalid Code!", vbCritical) cannot be evaluated to a value.
This would compile and work:
MsgBox ("Invalid Code!"), (vbCritical)
But would definitely look silly. Avoid redundant parentheses.
The most serious consequence of using parentheses inappropriately can best be demonstrated by code such as:
Sub Test()
Dim r As Range
Set r = Range("A1")
TestSub r
TestSub (r)
End Sub
Sub TestSub(parm As Range)
MsgBox parm.Address
End Sub
In that code TestSub r correctly passes a range object to TestSub. However, placing parentheses around the r, i.e. TestSub (r) causes VBA to evaluate r using its Value property and is therefore equivalent to TestSub r.Value. This then gives an error as it is passing a Variant (maybe a Variant/Double with a value of 123.45) to a subroutine that is expecting a Range.
It is basically just incorrect syntax to enclose parameters to a Subroutine within parentheses. They should only be used when a Function is returning a value.
P.S. I apologise that my example is Excel VBA. I hadn't noticed that the question was Word VBA, plus I could knock up an Excel example quicker than I could research Word VBA enough to give an example in it. The principle is the same in both though.
This question already has an answer here:
Array argument must be ByRef
(1 answer)
Closed 6 years ago.
Given the following code:
I can not seem to successfully pass a Range Object Variable from one sub-function to another. I spent an entire day researching, and experimenting before I swallowed pride and came here.
Please read the comments below, and reply with any ideas you have regarding why the LAST two lines will not behave.
Public Sub doSomethingToRows(ROI As Range)
*'do Something with the cell values within the supplied range*
End Sub
'
Public Sub testDoAltRows()
Dim RegionOfInterest As Range 'is this an object or not?
'*The following yields: Class doesn't support Automation (Error 430)*
'*Set RegionOfInterest = New Worksheet 'this just gives an error*
Set RegionOfInterest = Worksheets("Sheet1").Range("A1")
RegionOfInterest.Value = 1234.56 '*okay, updates cell A1*
Set RegionOfInterest = Worksheets("Sheet1").Range("B5:D15")
RegionOfInterest.Columns(2).Value = "~~~~~~" '*okay*
'doSomethingToRows (RegionOfInterest) 'why do I get "OBJECT IS REQUIRED" error?
doSomethingToRows (Worksheets("Sheet1").Range("B5:C15")) 'but this executes okay
End Sub
From the msdn documentation of the Call keyword statement,
Remarks
You are not required to use the Call keyword when calling a procedure.
However, if you use the Call keyword to call a procedure that requires
arguments, argumentlist must be enclosed in parentheses. If you omit
the Call keyword, you also must omit the parentheses around
argumentlist. If you use either Call syntax to call any intrinsic or
user-defined function, the function's return value is discarded.
To pass a whole array to a procedure, use the array name followed by
empty parentheses.
From a practical standpoint, even though Subs can be called with or without the "Call" keyword, it makes sense to pick one way and stick with it as part of your coding style. I agree with Comintern - it is my opinion, based on observation of modern VBA code, that using the "Call" keyword should be considered deprecated. Instead, invoke Subs without parenthesis around the argument list.
And now the answer to the important question:
Why does your code throw an error?
Take for example the following Subroutine:
Public Sub ShowSum(arg1 As Long, arg2 As Long)
MsgBox arg1 + arg2
End Sub
We have established that, if not using the Call keyword, Subs must be invoked like so:
ShowSum 45, 37
What happens if it were instead called like ShowSum(45, 37)? Well, you wouldn't even be able to compile as VBA immediately complains "Expected =". This is because the VBA parser sees the parenthesis and decides that this must be a Function call, and it therefore expects you to be handling the return value with an "=" assignment statement.
What about a Sub with only one argument? For example:
Public Sub ShowNum(arg1 As Long)
MsgBox arg1
End Sub
The correct way to call this Sub is ShowNum 45. But what if you typed this into the VBA IDE: ShowNum(45)? As soon as you move the cursor off of the line, you'll notice that VBA adds a space between the Sub name and the opening parenthesis, giving you a crucial clue as to how the line of code is actually being interpreted:
ShowNum (45)
VBA is not treating those parenthesis as if they surrounded the argument list - it is instead treating them as grouping parenthesis. MOST of the time, this wouldn't matter, but it does in the case of Objects which have a default member.
To see the problem this causes, try running the following:
Dim v As Variant
Set v = Range("A1")
Set v = (Range("A1")) '<--- type mismatch here
Notice that you get a "Type Mismatch" on the marked line. Now add those two statements to the watch window and look at the "Type" column:
+-------------+-----+--------------+
| Expression |Value| Type |
+-------------+-----+--------------+
|Range("A1") | |Object/Range |
|(Range("A1"))| |Variant/String|
+-------------+-----+--------------+
When you surround an Object with grouping parenthesis, its default property is evaluated - in the case of the Range object, it is the Value property.
So it's really just a coincidence that VBA allowed you to get away with "putting parenthesis around the argumentlist" - really, VBA just interprets this as grouping parenthesis and evaluates the value accordingly. You can see by trying the same thing on a Sub with multiple parameters that it is invalid in VBA to invoke a Sub with parenthesis around the argument list.
#PaulG
Try this:
Public Sub Main()
Debug.Print TypeName(Range("A1"))
Debug.Print TypeName((Range("A1")))
End Sub
okay, I knew after I posted this question I'd be struck by lighting and receive an answer.
When passing an object VARIABLE to a sub-function and wishing to use parentheses "()", one must use CALL! Thus the correction to my code sample is:
**CALL doSomethingToRows(RegionOfInterest)**
Thank you!
Maybe we're talking about different things, but here's an example to make it a bit clearer what I mean.
Option Explicit
Sub TestDisplay()
Dim r As Range
'Create some range object
Set r = Range("A1")
'Invoke with Call.
Call DisplaySomething(r)
'Invoke without Call.
DisplaySomething r
End Sub
Sub DisplaySomething(ByVal Data As Range)
Debug.Print "Hi my type is " & TypeName(Data)
End Sub
Both calls work perfectly. One with Call and the other without.
Edit:
#Conintern. Thanks for explaining that. I see what is meant now.
However, I still respectively disagree.
If I declare the following:
Function DisplaySomething(ByVal Data As String)
DisplaySomething = "Hi my type is " & TypeName(Data)
End Function
and invoke it:
Debug.print DisplaySomething(Range("A1"))
I believe that Excel has been clever and converted to a string. It can do that by invoking the Default Parameter and can convert to a string.
However, as in the original parameter example, If I declare the following:
Function DisplaySomething(ByVal Data As Range)
DisplaySomething = "Hi my type is " & TypeName(Data)
End Function
There is no call on the Default Parameter, however it is called, because Excel was able to resolve it to that type.
Function DisplaySomething(ByVal Data As Double)
DisplaySomething = "Hi my type is " & TypeName(Data)
End Function
will return a double because it was able to coerce to a double.
Indeed in those examples the Default was called.
But in this example we are defining as Range. No Default called there however it is invoked - brackets or no brackets.
I believe this is more to do with Excel and data coercion.
Similar to the following:
Public Function Test(ByVal i As String) As Integer
Test = i
End Function
and invoking with:
Debug.print Test("1")
BTW, yes I know this isn't an object without a Default parmeter. Im pointing out data coercion. Excel does its best to resolve it.
Could be wrong mind you...