Perf wrapper for Excel VBA

Question

Spoiler

This code is actually BAD for performances! So don't use it! ;)

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For a while now, I've been using this wrapper to avoid retyping most of it :

Public Sub PerfWrap(SubNameToRun As String, _
 Optional ByVal DispStatusBar As Boolean = False, _
 Optional ArgumentsToPass As String = vbNullString)
 Dim aWB As Workbook, _
 ActiveSH As Worksheet, _
 ScreenUpdateState As Boolean, _
 StatusBarState As Boolean, _
 CalcState As XlCalculation, _
 EventsState As Boolean, _
 DisplayPageBreakState As Boolean
 Set aWB = ActiveWorkbook
 Set ActiveSH = aWB.ActiveSheet
 DoEvents
 With Application
 ScreenUpdateState = .ScreenUpdating
 StatusBarState = .DisplayStatusBar
 CalcState = .Calculation
 EventsState = .EnableEvents
 DoEvents
 .ScreenUpdating = False
 .DisplayStatusBar = DispStatusBar
 .Calculation = xlCalculationManual
 .EnableEvents = False
 End With
 DisplayPageBreakState = ActiveSH.DisplayPageBreaks
 ActiveSH.DisplayPageBreaks = False
 If ArgumentsToPass <> vbNullString Then
 Application.Run SubNameToRun, ArgumentsToPass
 Else
 Application.Run SubNameToRun
 End If
 DoEvents
 ActiveSH.Activate
 ActiveSH.DisplayPageBreaks = DisplayPageBreakState
 With Application
 .ScreenUpdating = ScreenUpdateState
 .DisplayStatusBar = StatusBarState
 .StatusBar = vbNullString
 .Calculation = CalcState
 .EnableEvents = EventsState
 End With
End Sub

I use it like this :

Public Sub Launcher_CopyAndUpdate()
 Call PerfWrap("CopyAndUpdate_Templates", True)
End Sub

Or to pass arguments to the runned procedure :

Public Sub Launcher_Update()
 Call PerfWrap("Update_Templates", True, "Arg1, Arg2")
End Sub

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I was wondering if :

• it can be improved regarding performances
• converted as a function to return the value sent by the runned function

Anyhow, any input or opinion is very welcome! :)

• sysmod: I do what Mat said: "You could even wrap that toggle behavior in a class, encapsulate the state [...] and use the Class_Terminate handler to revert back to original state, that way the calling code couldn't even "forget" to toggle it back:"
• R3uK: @sysmod : Do you have this visible somewhere to check it out?

Answer 1

First, I'd like to echo @Mat'sMug's distaste for your multi-lined Dim statements. There's absolutely no reason to do this at all having them prefixed with Dim makes it completely obvious that I'm looking at a declaration block. It took me a good minute to realize that it wasn't a continuation of Sub declaration, because the Dim literally disappears into a huge wall of code. You aren't saving any time typing it either - last time I checked, Dim and , _ were both 3 characters, and the former is a lot easier to type on a qwerty keyboard.

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The other answers hint around the performance, but I'll just come right out and say it. Your Sub should really be named the AntiPerfWrap. First, every single call that Application.Run makes is late bound - even for Excel objects. It has to be, because like CallByName, it is forced to call IDispactch.GetIDsOfNames on itself. This is always slower than an early bound call - period, end of discussion.

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You always cache the ActiveWorkbook and ActiveSheet regardless of whether it is necessary or not. I would guess that roughly 1% of all the code I've written requires this. Same thing with .Calculation. Same thing with .EnableEvents. Do I write another PerfWrapWithEvents if I need that turned on? Or maybe PerfWrapWithEventsAllowCalculation? None of this work is free, and it seems like a jumbled collection of "this will make your code go faster anecdotes" collected from SO comments. The cargo cult has found thier messiah in this wrapper.

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DoEvents is not free. In fact it's the complete opposite. It yields the processor to every other thread that needs to clear it's event queue. It also makes absolutely no sense to call DoEvents when you've explicitly disabled 95% of the functionality that would make the call useful.

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Brass tacks time - let's see how much overhead this wrapper really adds. This is the called routine:

Public Sub UnderTest()
 Dim i As Long
 For i = 1 To 10
 Debug.Print i
 Next
End Sub

And the baseline benchmark:

Public Sub BenchmarkOne()
 Dim starting As Single
 starting = Timer
 Dim i As Long
 For i = 1 To 100
 Sheet1.UnderTest
 Next
 Debug.Print "Unwrapped: " & Timer - starting
End Sub

Unwrapped: 0.8515625

Public Sub BenchmarkTwo()
 Dim starting As Single
 starting = Timer
 Dim i As Long
 For i = 1 To 100
 PerfWrap "Sheet1.UnderTest"
 Next
 Debug.Print "Wrapped: " & Timer - starting
End Sub

Wrapped: 6.492188

Ouch.

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Conclusion - Burn it. Burn it with fire. The premise behind the code is that there is a common set of operations that you can do to "speed up" code. In fact, this is never true. In reality, you are turning off Excel functionality that can slow down code. There's a big difference. If you approach performance issues by looking outside of code that you've written, you're starting out looking in the wrong direction. A catch-all "solution" for performance simply doesn't exist, so I wouldn't pretend to be providing it. The best way to look at it is to imagine that any code under performance review to be copied and pasted in place of this...

If ArgumentsToPass <> vbNullString Then
 Application.Run SubNameToRun, ArgumentsToPass
Else
 Application.Run SubNameToRun
End If

...then do a code review on the entire thing. Ask yourself, "In the context of the full Sub, what is the reason for every single line of code other than part above"? I'm guessing that in roughly 99.99% of cases, there won't be a good answer for all of them.

• R3uK: OUCH!!! Indeed! I couldn't imagine that it was THAT BAD... I knew that it wasn't good, but in fact it is quite an horror show!^^ I didn't know that Application.Run was so bad, and was just looking for something easier to use for the multiples UI actions. Anyway, thx for showing me how BAD it was! I'll get rid of this right now! ;)
• Brandon Barney: "The cargo cult has found thier messiah in this wrapper." I want to put this on my wall.

Answer 2

You're inverting the caller/callee chain here. There are pro's and con's, but IMO more con's than pro's - Application.Run is a performance hit in the first place, and with the stringly-typed parameters you lose compile-time validation of your code... which I would do anything to try and preserve as much as possible.

Another downside is that it's not going to work on class methods, so you can't have an object that's responsible for interacting with a worksheet - may or may not be a problem, but utility code shouldn't be driving design decisions of its calling code that way.

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This declaration is annoying:

Dim aWB As Workbook, _
 ActiveSH As Worksheet, _
 ScreenUpdateState As Boolean, _
 StatusBarState As Boolean, _
 CalcState As XlCalculation, _
 EventsState As Boolean, _
 DisplayPageBreakState As Boolean

You (or a maintainer) can't add a comment on any of those. This is probably going to break syntax highlighting in this post, but...

Dim aWB As Workbook, _ 'a comment here is illegal
 ActiveSH As Worksheet, _
 ScreenUpdateState As Boolean, _
 StatusBarState As Boolean, _
 CalcState As XlCalculation, _
 EventsState As Boolean, _
 DisplayPageBreakState As Boolean

Here's how the VBE sees it:

compile error

And if you manage to squeeze a legit comment in there, well you better hope you have Option Explicit specified:

Dim aWB As Workbook, _
 ActiveSH As Worksheet, _
 ScreenUpdateState As Boolean 'oh, and this one is legal, but... _
 StatusBarState As Boolean, _
 CalcState As XlCalculation, _
 EventsState As Boolean, _
 DisplayPageBreakState As Boolean

I would simply avoid cramming multiple declarations in a single statement, there's no real reason to do that... and there are real reasons to avoid it:

Compile error: too many line continuations

Variables should be declared close to their first use anyway, not in a wall of declarations at the top of the procedure.

FWIW with Rubberduck (a COM add-in for the VBE that I [and other fellow VBA reviewers] is [are] working on), that's a one-click fix:

Inspection Results > Fix > Separate multiple declarations into multiple instructions

That instantly turns the statement into this:

Dim aWB As Workbook
Dim ActiveSH As Worksheet
Dim ScreenUpdateState As Boolean
Dim StatusBarState As Boolean
Dim CalcState As XlCalculation
Dim EventsState As Boolean
Dim DisplayPageBreakState As Boolean

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You don't need the the aWB local variable at all (a terrible name IMO), since you already have ActiveSH (which I'd probably rename to originalActiveSheet), and its .Parent member points to the originally active workbook.

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It's not clear why SubNameToRun and ArgumentsToPass are passed ByRef (implicitly), when DispStatusBar is explicitly ByVal - all parameters could very well be ByVal here.

Actually - and given the 30 optional parameters of Application.Run that would look much uglier, but ArgumentsToPass would make a much friendlier API if it were a ParamArray parameter; that way you could keep type safety for your arguments, which means you could pass arguments that can't be implicitly or explicitly converted to a String - e.g. a Range object.

Not being able to pass an object parameter is a serious showstopper limitation IMO.

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I think it's a nice idea, but it's way too limited. A more flexible solution would be a simple ToggleWaitMode procedure that toggles ScreenUpdating, DisplayStatusBar, Calculation, EnableEvents, allows specifying an optional StatusBar message, and heck, that toggles the Cursor to/from xlWait as well.

You could even wrap that toggle behavior in a class, encapsulate the state (although that's a leaky abstraction, these things are all global really), and use the Class_Terminate handler to revert back to original state, that way the calling code couldn't even "forget" to toggle it back:

With WaitWorker.Init(statusText:="Please wait...", disableEvents:=True)
 'do stuff
End With

That way you don't need to do Application.Run, so it works with class module callers, and you're not passing a stringly-typed list of parameters either, so the caller can still do everything it wants: you're not interfering with the caller.

• Vogel612: you is working on Rubberduck?
• Mathieu Guindon: @Vogel612 yes, I is =)
• R3uK: Thx for the valuable inputs! I didn't though of the object parameters when I wrote the base that I reused more recently for this one (as I only use this on main program called by buttons), but indeed it is a deal-breaker for more general use (and ParamArray is a pretty common coding method across languages) ! ToggleWaitMode procedure could be interesting with a few Public variables, but I'm pretty intrigued by the class approach, and wondering what do you mean by "leaky abstraction"?
• Brandon Barney: @Mat'sMug Out of curiosity, why should declarations be close to their use? I always thought it was opposite, but that may just be personal preference. I tend to declare whatever is easiest to use at the beginning, and then refactor for performance at the end. To this end, declaring them in a block at the top makes it much easier for me to see if I have gotten out of control and if I need to refactor.
• Mathieu Guindon: Oh, absolutely!! ...except if your boss is non-technical and the app is business-critical and you're just not authorized to check in non-functional changes that "don't bring any business value or fix any actual problem" =)

Answer 3

I'm uncertain of the efficiencies in a single wrapper like this. In developing applications with multiple modules and classes, I'm often needing to disable screen updates and such but without extremely careful planning I used to always step on my own toes. So I developed two routines that allow me to disable and enable Excel application level updates and give me enough tracking debug.

Using the calls becomes as easy as sprinkling these calls around:

Sub SomeImportantWork()
 DisableUpdates
 '--- do stuff
 OtherImportantWork
 EnableUpdates
End Sub
Sub OtherImportantWork()
 DisableUpdates debugMsg:="enter OtherImportantWork"
 '--- work more stuff
 EnableUpdates debugMsg:="leave OtherImportantWork"
End Sub

My idea has been to not worry about whether I've call disable/enable, but only to make sure those calls are paired around any code that requires that protection.

At the module level, I define a structure and a private variable to hold any previous state information:

Option Explicit
Private Type SavedState
 screenUpdate As Boolean
 calculationType As XlCalculation
 eventsFlag As Boolean
 callCounter As Long
End Type
Private previousState As SavedState
Private Const DEBUG_MODE = True

Then when I want to disable application updates, I call:

Public Sub DisableUpdates(Optional debugMsg As String = "", _
 Optional forceZero As Boolean = False)
 With Application
 '--- capture previous state if this is the first time
 If forceZero Or (previousState.callCounter = 0) Then
 previousState.screenUpdate = .ScreenUpdating
 previousState.calculationType = .Calculation
 previousState.eventsFlag = .EnableEvents
 previousState.callCounter = 0
 End If
 '--- now turn it all off and count
 .ScreenUpdating = False
 .Calculation = xlCalculationManual
 .EnableEvents = False
 previousState.callCounter = previousState.callCounter + 1
 '--- optional stuff
 If DEBUG_MODE Then
 Debug.Print "Updates disabled (" & previousState.callCounter & ")";
 If Len(debugMsg) > 0 Then
 Debug.Print debugMsg
 Else
 Debug.Print vbCrLf
 End If
 End If
 End With
End Sub

And the mirroring method to re-enable is:

Public Sub EnableUpdates(Optional debugMsg As String = "", _
 Optional forceZero As Boolean = False)
 With Application
 '--- countdown!
 If previousState.callCounter >= 1 Then
 previousState.callCounter = previousState.callCounter - 1
 Else
 '--- shouldn't get here
 Debug.Print "EnableUpdates ERROR: reached callCounter = 0"
 End If
 '--- only re-enable updates if the counter gets to zero
 ' or we're forcing it
 If forceZero Or (previousState.callCounter = 0) Then
 .ScreenUpdating = previousState.screenUpdate
 .Calculation = previousState.calculationType
 .EnableEvents = previousState.eventsFlag
 End If
 '--- optional stuff
 If DEBUG_MODE Then
 Debug.Print "Updates enabled (" & previousState.callCounter & ")";
 If Len(debugMsg) > 0 Then
 Debug.Print debugMsg
 Else
 Debug.Print vbCrLf
 End If
 End If
 End With
End Sub

As you can see, I have a private module flag to turn on debug messages (DEBUG_MODE) if I need them and turn them off for production. You can turn this into a compiler directive flag if you feel you need a (small) runtime performance boost.

The callCounter lets me keep track of my "updates call stack". This is especially usedful when I started calling some library routines I had and those calls got rather deep. It certainly helped to track it down.'

Also, I can go into the Immediate window at any time and type EnableUpdates(forceZero=True) and get back to a known state manually.

• R3uK: Thx for your input, that what I thought about when reading the other answers. I like your DEBUG_MODE which could be pretty handy indeed!