I have Class with bunch of Properties which looks almost the same.
If Not gXXXReady Then 'Check global boolean variable gXXXReady
call Object.SubProcedureYYY()
End If
set XXX = gXXX ' Use global variable as property value
End Property
What is differnet between these Properties is XXX and ``YYY`
Is there some way how to simplify this code? Something like:
Private Function UniversalGetFunc(ByVal VarName As String, ByVal MethodName As String)
If Not GetVarByName(VarName) Then
call Object.CallProcedureByName("SubProcedure" & MethodName)
End If
End Function
...
' Usage
Property Get XXX() As Collection
UniversalGetFunc("XXX", "YYY")
set XXX = gXXX
End Property
Where GetVarByName and CallProcedureByName are (obviously) fictitious functions. Object is same for all my Properties, so is not neccesary to pass it to UniversalGetFunc.
It is even possible with (Office VBA?)
Thank you!
PS: The
Related
Preface
About 10 years ago I started refactoring and improving the ChartSeries class of John Walkenbach. Unfortunately it seems that the original it is not available any more online.
Following the Rubberduck Blog for quite some time now I try to improve my VBA skills. But in the past I only have written -- I guess the experts would call it -- "script-like god-procedures" (because of not knowing better). So I am pretty new to classes and especially interfaces and factories.
Actual Questions
I try to refactor the whole class by dividing it into multiple classes also using interfaces and than also adding unit tests. For just reading the parts of a formula it would be sufficient to get the Series.Formula and then do all the processing. So it would be nice to call the Run sub in the Create function. But everything I tried so far to do so failed. Thus, I currently running Run in all Get properties etc. (and test, if the formula changed and exit Run than. Is this possible and when yes, how?
Second, to add unit tests -- of course using rubberduck for them -- I currently rely on real Charts/ChartObjects. How do I create a stub/mock/fake for a Series? (Sorry, I don't know the correct term.)
And here a simplified version of the code.
Many thanks in advance for any help.
normal module
'#Folder("ChartSeries")
Option Explicit
Public Sub ExampleUsage()
Dim wks As Worksheet
Set wks = ThisWorkbook.Worksheets(1)
Dim crt As ChartObject
Set crt = wks.ChartObjects(1)
Dim srs As Series
Set srs = crt.Chart.SeriesCollection(3)
Dim MySeries As IChartSeries
Set MySeries = ChartSeries.Create(srs)
With MySeries
Debug.Print .XValues.FormulaPart
End With
End Sub
IChartSeries.cls
'#Folder("ChartSeries")
'#Interface
Option Explicit
Public Function IsSeriesAccessible() As Boolean
End Function
Public Property Get FullFormula() As String
End Property
Public Property Get XValues() As ISeriesPart
End Property
'more properties ...
ChartSeries.cls
'#PredeclaredId
'#Exposed
'#Folder("ChartSeries")
Option Explicit
Implements IChartSeries
Private Type TChartSeries
Series As Series
FullSeriesFormula As String
OldFullSeriesFormula As String
IsSeriesAccessible As Boolean
SeriesParts(eElement.[_First] To eElement.[_Last]) As ISeriesPart
End Type
Private This As TChartSeries
Public Function Create(ByVal Value As Series) As IChartSeries
'NOTE: I would like to run the 'Run' sub somewhere here (if possible)
With New ChartSeries
.Series = Value
Set Create = .Self
End With
End Function
Public Property Get Self() As IChartSeries
Set Self = Me
End Property
Friend Property Let Series(ByVal Value As Series)
Set This.Series = Value
End Property
Private Function IChartSeries_IsSeriesAccessible() As Boolean
Call Run
IChartSeries_IsSeriesAccessible = This.IsSeriesAccessible
End Function
Private Property Get IChartSeries_FullFormula() As String
Call Run
IChartSeries_FullFormula = This.FullSeriesFormula
End Property
Private Property Get IChartSeries_XValues() As ISeriesPart
Call Run
Set IChartSeries_XValues = This.SeriesParts(eElement.eXValues)
End Property
'more properties ...
Private Sub Class_Initialize()
With This
Dim Element As eElement
For Element = eElement.[_First] To eElement.[_Last]
Set .SeriesParts(Element) = New SeriesPart
Next
End With
End Sub
Private Sub Class_Terminate()
With This
Dim Element As LongPtr
For Element = eElement.[_First] To eElement.[_Last]
Set .SeriesParts(Element) = Nothing
Next
End With
End Sub
Private Sub Run()
If Not GetFullSeriesFormula Then Exit Sub
If Not HasFormulaChanged Then Exit Sub
Call GetSeriesFormulaParts
End Sub
'(simplified version)
Private Function GetFullSeriesFormula() As Boolean
GetFullSeriesFormula = False
With This
'---
'dummy to make it work
.FullSeriesFormula = _
"=SERIES(Tabelle1!$B$2,Tabelle1!$A$3:$A$5,Tabelle1!$B$3:$B$5,1)"
'---
.OldFullSeriesFormula = .FullSeriesFormula
.FullSeriesFormula = .Series.Formula
End With
GetFullSeriesFormula = True
End Function
Private Function HasFormulaChanged() As Boolean
With This
HasFormulaChanged = (.OldFullSeriesFormula <> .FullSeriesFormula)
End With
End Function
Private Sub GetSeriesFormulaParts()
Dim MySeries As ISeriesFormulaParts
'(simplified version without check for Bubble Chart)
Set MySeries = SeriesFormulaParts.Create( _
This.FullSeriesFormula, _
False _
)
With MySeries
Dim Element As eElement
For Element = eElement.[_First] To eElement.[_Last] - 1
This.SeriesParts(Element).FormulaPart = _
.PartSeriesFormula(Element)
Next
'---
'dummy which normally would be retrieved
'by 'MySeries.PartSeriesFormula(eElement.eXValues)'
This.SeriesParts(eElement.eXValues).FormulaPart = _
"Tabelle1!$A$3:$A$5"
'---
End With
Set MySeries = Nothing
End Sub
'more subs and functions ...
ISeriesPart.cls
'#Folder("ChartSeries")
'#Interface
Option Explicit
Public Enum eEntryType
eNotSet = -1
[_First] = 0
eInaccessible = eEntryType.[_First]
eEmpty
eInteger
eString
eArray
eRange
[_Last] = eEntryType.eRange
End Enum
Public Property Get FormulaPart() As String
End Property
Public Property Let FormulaPart(ByVal Value As String)
End Property
Public Property Get EntryType() As eEntryType
End Property
Public Property Get Range() As Range
End Property
'more properties ...
SeriesPart.cls
'#PredeclaredId
'#Folder("ChartSeries")
'#ModuleDescription("A class to handle each part of the 'Series' string.")
Option Explicit
Implements ISeriesPart
Private Type TSeriesPart
FormulaPart As String
EntryType As eEntryType
Range As Range
RangeString As String
RangeSheet As String
RangeBook As String
RangePath As String
End Type
Private This As TSeriesPart
Private Property Get ISeriesPart_FormulaPart() As String
ISeriesPart_FormulaPart = This.FormulaPart
End Property
Private Property Let ISeriesPart_FormulaPart(ByVal Value As String)
This.FormulaPart = Value
Call Run
End Property
Private Property Get ISeriesPart_EntryType() As eEntryType
ISeriesPart_EntryType = This.EntryType
End Property
Private Property Get ISeriesPart_Range() As Range
With This
If .EntryType = eEntryType.eRange Then
Set ISeriesPart_Range = .Range
Else
' Call RaiseError
End If
End With
End Property
Private Property Set ISeriesPart_Range(ByVal Value As Range)
Set This.Range = Value
End Property
'more properties ...
Private Sub Class_Initialize()
This.EntryType = eEntryType.eNotSet
End Sub
Private Sub Run()
'- set 'EntryType'
'- If it is a range then find the range parts ...
End Sub
'a lot more subs and functions ...
ISeriesParts.cls
'#Folder("ChartSeries")
'#Interface
Option Explicit
Public Enum eElement
[_First] = 1
eName = eElement.[_First]
eXValues
eYValues
ePlotOrder
eBubbleSizes
[_Last] = eElement.eBubbleSizes
End Enum
'#Description("fill me")
Public Property Get PartSeriesFormula(ByVal Element As eElement) As String
End Property
SeriesFormulaParts.cls
'#PredeclaredId
'#Exposed
'#Folder("ChartSeries")
Option Explicit
Implements ISeriesFormulaParts
Private Type TSeriesFormulaParts
FullSeriesFormula As String
IsSeriesInBubbleChart As Boolean
WasRunCalled As Boolean
SeriesFormula As String
RemainingFormulaPart(eElement.[_First] To eElement.[_Last]) As String
PartSeriesFormula(eElement.[_First] To eElement.[_Last]) As String
End Type
Private This As TSeriesFormulaParts
Public Function Create( _
ByVal FullSeriesFormula As String, _
ByVal IsSeriesInBubbleChart As Boolean _
) As ISeriesFormulaParts
'NOTE: I would like to run the 'Run' sub somewhere here (if possible)
With New SeriesFormulaParts
.FullSeriesFormula = FullSeriesFormula
.IsSeriesInBubbleChart = IsSeriesInBubbleChart
Set Create = .Self
End With
End Function
Public Property Get Self() As ISeriesFormulaParts
Set Self = Me
End Property
'#Description("Set the full series formula ('ChartSeries')")
Public Property Let FullSeriesFormula(ByVal Value As String)
This.FullSeriesFormula = Value
End Property
Public Property Let IsSeriesInBubbleChart(ByVal Value As Boolean)
This.IsSeriesInBubbleChart = Value
End Property
Private Property Get ISeriesFormulaParts_PartSeriesFormula(ByVal Element As eElement) As String
'NOTE: Instead of running 'Run' here, it would be better to run it in 'Create'
Call Run
ISeriesFormulaParts_PartSeriesFormula = This.PartSeriesFormula(Element)
End Property
'(replaced with a dummy)
Private Sub Run()
If This.WasRunCalled Then Exit Sub
'extract stuff from
This.WasRunCalled = True
End Sub
'a lot more subs and functions ...
You can already!
Public Function Create(ByVal Value As Series) As IChartSeries
With New ChartSeries <~ With block variable has access to members of the ChartSeries class
.Series = Value
Set Create = .Self
End With
End Function
...only, like the .Series and .Self properties, it has to be a Public member of the ChartSeries interface/class (the line is blurry in VBA, since every class has a default interface / is also an interface).
Idiomatic Object Assignment
A note about this property:
Friend Property Let Series(ByVal Value As Series)
Set This.Series = Value
End Property
Using a Property Let member to Set an object reference will work - but it isn't idiomatic VBA code anymore, as you can see in the .Create function:
.Series = Value
If we read this line without knowing about the nature of the property, this looks like any other value assignment. Only problem is, we're not assigning a value, but a reference - and reference assignments in VBA are normally made using a Set keyword. If we change the Let for a Set in the Series property definition, we would have to do this:
Set .Series = Value
And that would look much more readily like the reference assignment it is! Without it, there appears to be implicit let-coercion happening, and that makes it ambiguous code: VBA requires a Set keyword for reference assignments, because any given object can have a paraterless default property (e.g. how foo = Range("A1") implicitly assigns foo to the Value of the Range).
Caching & Responsibilities
Now, back to the Run method - if it's made Public on the ChartSeries class, but not exposed on the implemented IChartSeries interface, then it's a member that can only be invoked from 1) the ChartSeries default instance, or 2) any object variable that has a ChartSeries declared type. And since our "client code" is working off IChartSeries, we can guard against 1 and shrug off 2.
Note that the Call keyword is superfluous, and the Run method is really just pulling metadata from the encapsulated Series object, and caching it at instance level - I'd give it a name that sounds more like "refresh cached properties" than "run something".
Your hunch is a good one: Property Get should be a simple return function, without any side-effects. Invoking a method that scans an object and resets instance state in a Property Get accessor makes it side-effecting, which is a design smell - in theory.
If Run is invoked immediately after creation before the Create function returns the instance, then this Run method boils down to "parse the series and cache some metadata I'll reuse later", and there's nothing wrong with that: invoke it from Create, and remove it from the Property Get accessors.
The result is an object whose state is read-only and more robustly defined; the counterpart of that is that you now have an object whose state might be out of sync with the actual Excel Series object on the worksheet: if code (or the user) tweaks the Series object after the IChartSeries is initialized, the object and its state is stale.
One solution is to go out of your way to identify when a series is stale and make sure you keep the cache up-to-date.
Another solution would be to remove the problem altogether by no longer caching the state - that would mean one of two things:
Generating the object graph once on creation, effectively moving the caching responsibility to the caller: calling code gets a read-only "snapshot" to work with.
Generating a new object graph out of the series metadata, every time the calling code needs it: effectively, it moves the caching responsibility to the caller, which isn't a bad idea at all.
Making things read-only removes a lot of complexity! I'd go with the first option.
Overall, the code appears nice & clean (although it's unclear how much was scrubbed for this post) and you appear to have understood the factory method pattern leveraging the default instance and exposing a façade interface - kudos! The naming is overall pretty good (although "Run" sticks out IMO), and the objects look like they each have a clear, defined purpose. Good job!
Unit Testing
I currently rely on real Charts/ChartObjects. How do I create a stub/mock/fake for a Series? (Sorry, I don't know the correct term.)
Currently, you can't. When if/when this PR gets merged, you'll be able to mock Excel's interfaces (and much, much more) and write tests against your classes that inject a mock Excel.Series object that you can configure for your tests' purposes... but until then, this is where the wall is.
In the mean time, the best you can do is wrap it with your own interface, and stub it. In other words, wherever there's a seam between your code and Excel's object model, we slip an interface between the two: instead of taking in a Excel.Series object, you'd be taking in some ISeriesWrapper, and then the real code would be using an ExcelSeriesWrapper that works off an Excel.Series, and the test code might be using a StubSeriesWrapper whose properties return either hard-coded values, or values configured by tests: the code that works at the seam between the Excel library and your project, can't be tested - and we woulnd't want to anyway, because then we'd be testing Excel, not our own code.
You can see this in action in the example code for the next upcoming RD News article here; that article will discuss exactly this, using ADODB connections. The principle is the same: none of the 94 unit tests in that project ever open any actual connection, and yet with dependency injection and wrapper interfaces we're able to test every single bit of functionality, from opening a database connection to committing a transaction... without ever hitting an actual database.
is there way how to make class working similar to Arrays?
Let's say, I have Class (e.g. Workers) where main property is array of the Workers, nothing else.
Then I'm filling the class as follows
Dim wks as new Workers
wks.add("Worker1")
wks.add("Worker2")
wks.add("Worker3")
Then in Workers Class module:
Private Workers as Variant
Public Function add(ByVal val As Variant) As Long
ReDim Preserve Workers(LBound(Workers) To UBound(Workers) + 1)
Workers(UBound(Workers)) = val
add = UBound(Workers) - LBound(Workers) +1
End Function
Workers representation -> {"Worker1", "Worker2", "Worker3"}
Then I want to access Worker by its index. I know, how to access it by e.g wks.getWorker(1) but what I want to do, is to access it directly by wks(1) which should return "Worker 1". Example above looks, that usual Array or Collection can be used, but I have many internal methods done, only what I'm missing is to access Workers property to read/write directly by its index number.
Is it possible?
Edit
After transfer to Collections, Class looks like:
Option Explicit
Private Workers As Collection
Private Sub Class_Initialize()
Set Workers = New Collection
End Sub
Public Function add(ByVal val As Variant) As Long
Workers.add val
End Function
Public Property Get Item(Index As Integer) As Variant
Item = Workers(Index)
End Property
Public Property Set Item(Index As Integer, Value As Variant)
Workers.Remove Index
Workers.add Value, Before:=Index
End Property
with hidden attributes Attribute Item.VB_UserMemId = 0 at Getter and Setter.
Getting works fine:
Dim wks As New Workers
wks.add "Worker1"
wks.add "Worker2"
wks.add "Worker3"
Debug.Print wks(2) ' <-- OK here
'wks(2) = "Second Worker" ' <-- By debugging this go to Getter not Setter and after Getter is done, it allerts with Runtime error '424': Object required
Set wks(2) = "Second Worker" ' <-- This alert immediately Compile error: Object required on "Second Worker" string
Debug.Print wks(2)
Prints "Worker2" into console, thanks for this, but still I'm not able to set a new value to the required Index of the Workers Collection.
You could use a default member in VBA. Though you can't make the default memeber directly through VBA editor, but you can use any text editor.
Export your class from VBA editor, i.e. File->Export File
Open your exported class in Notepad (or any text editor)
Add this attribute line on your method or property you want to make it default. Attribute Item.VB_UserMemId = 0
You can for example make getWorker default member as.
Public Function GetWorker(Index As Integer) As Worker
Attribute Item.VB_UserMemId = 0
GetWorker = Workers(Index)
End Function
you can then use it like.
Set wk = wks(1)
Here is some detail about default members
http://www.cpearson.com/excel/DefaultMember.aspx
Edits
An example to make Getter/Setter as default member
Public Property Get Item(Index as Integer) as Worker
Attribute Item.VB_UserMemId = 0
Set Item = Workers(Index)
End Property
Public Property Set Item(Index as Integer, Value as Worker)
Attribute Item.VB_UserMemId = 0
Set Workers(Index) = Value
End Property
I'm having a class module with some data:
Private sharedFolders() As String
Public Property Let SetSharedFolders(val As String)
Dim i As Integer
sharedFolders = Array("folder one", "folder two")
i = UBound(sharedFolders)
i = UBound(sharedFolders)
ReDim Preserve sharedFolders(i)
sharedFolders(i) = CStr(val)
End Property
Property Get GetSharedFolders()
GetSharedFolders = sharedFolders()
End Property
And I want to add something to this property from other module like this:
Sub PrepareData()
Dim e
Dim s
Dim a(2) As String
Set e = New Entry
a(0) = "add one"
a(1) = "add two"
For Each s In a
e.SetSharedFolders (s) 'Here comes exception
Next
For Each s In e.GetSharedFolders
Debug.Print s
Next
End Sub
But I receive an "wrong number of arguments or invalid property assignment vba" exception... Can anyone assist?
Addendum
Thanks to #AJD and #Freeflow to pointing out a mistake and idea to make it easier. Decided to make as like below.
Class Module:
Private sharedFolders As New Collection
Public Property Let SetSharedFolders(val As String)
If sharedFolders.Count = 0 Then ' if empty fill with some preset data and add new item
sharedFolders.Add "folder 1"
sharedFolders.Add "folder 2"
sharedFolders.Add CStr(val)
Else
sharedFolders.Add CStr(val)
End If
End Property
Property Get GetSharedFolders() As Collection
Set GetSharedFolders = sharedFolders
End Property
and regular module:
Sub AddData()
Dim e As New Entry ' creating an instance of a class
Dim s As Variant ' variable to loop through collection
Dim a(1) As String 'some array with data to insert
a(0) = "add one"
a(1) = "add two"
For Each s In a
e.SetSharedFolders = s
Next
For Each s In e.GetSharedFolders
Debug.Print s
Next
End Sub
Initially I thought the problem lies in this code:
i = UBound(sharedFolders)
i = UBound(sharedFolders)
ReDim Preserve sharedFolders(i)
sharedFolders(i) = CStr(val)
i is set twice to the same value, and then the sharedFolders is reDimmed to the same value it was before! Also, there is some trickery happening with the use of ix within a 0-based array.
But the problem is most likely how you have declared your variables.
For Each s In a
e.SetSharedFolders (s) 'Here comes exception
Next
s is a Variant, and a is a Variant. At this point VBA is trying to guess how to handle a For Each loop with two Variants. And then the improper call is made. The correct syntax is:
e.SetSharedFolders s '<-- no parenthesis
There are plenty of posts on StackOverflow explaining how to call routines and what the impact of the evaluating parenthesis are!
However, at this point we are only assuming it is passing in a single element of the array - it could be passing the full array itself (albeit unlikely).
And the third factor -
Public Property Let SetSharedFolders(val As String)
The parameter val is being passed ByRef and should be passed ByVal. This also has unintended side effects as I found out (Type mismatch trying to set data in an object in a collection).
Public Property Let SetSharedFolders(ByVal val As String)
All in all you have the perfect storm of ambiguity driving to an unknown result.
The answer here is to strongly type your variables. This removes about two layers of ambiguity and areas where errors can happen. In addition, this will slightly improve code execution.
Another aspect is to understand when you should pass something ByVal and when to use the default (preferably explicitly) ByRef.
And a final gratuitous hint: Use a Collection instead of an Array. Your code you have implies a Collection will be more efficient and easier to manage.
Addendum
(thanks to #FreeFlow):
If the OP changes the definition of sharedfolders to Variant rather than String() then the array statement will work as expected.
The line e.SetSharedFolders (s) will work fine if it is changed to e.SetSharedFolders = s because the method SetSharedFolders is a Let Property not a Sub. There are other errors but these two changes will make the code run.
I've searched all over to see if there is an easy answer to this question, but there doesn't seem to be...
I'm using Excel VBA 2003 (yes, I know it's out-of date, but I can't change this), and all I want to do is list the names and values of all the readable properties in a given custom class.
I'd like to do something like this:
Class definition (for class entitled cFooBar)
Option Explicit
Private pFoo As String
Private pBar As String
Public Property Get Foo() As String
Foo=pFoo
End Property
Public Property Get Bar() As String
Bar=pBar
End Property
Calling code
Dim myFooBar as cFooBar, P as Property
myFooBar=new cFooBar
For Each P in myFooBar.Properties
Debug.Print P.Name, P.Value
Next
Of course, this doesn't work because there doesn't seem to be a "Properties" collection member for custom classes (or at least not one that you can get at), and there isn't a "Property" type either.
Does anybody know a way around this?
TIA,
Campbell
As John mentions above, reflection is not supported in VBA. Here is a hack that I have used before. Basically you can create a Collection or Dictionary object to store your "properties" by name.
Option Explicit
Private pProperties As Object
Public Property Get Properties() As Object
Set Properties=pProperties
End Property
Public Property Let Properties(p as Object)
Set pProperties = p
End Property
Sub Class_Initialize()
Set pProperties = CreateObject("Scripting.Dictionary")
'Add/instantiate your properties here
pProperties("foo") = "this is foo"
pProperties("bar") = "this is bar"
End Sub
Calling code
Dim myFooBar As New cFooBar, P As Variant
For Each P In myFooBar.Properties.Keys()
Debug.Print P, myFooBar.Properties(P)
Next
I have been asked to modify an Excel sheet with some arcaic programming. I have decided to rewrite it rather then modify all of the many GOTO statments and static arrays. My background is in C# so it has been a bit of a challenge (note: I am sure the naming convention is bad, I am used to being able to use underscore to define private variables)
I am having trouble inializing an attribute of the type dictionary within a class that I have in a VBA application.
The shortened version of the class looks like this
Private pTerminalCode As String
Private pTerminalName As String
...... other attributes
Private pPayRoll As Dictionary
'Propeties
Public Property Get terminalCode() As String
terminalCode = pTerminalCode
End Property
Public Property Let terminalCode(Value As String)
pTerminalCode = Value
End Property
....... more properties
Public Property Get headCount() As Dictionary
headCount = pHeadCount
End Property
Public Property Let headCount(Value As Dictionary)
pHeadCount = Value
End Property
When I try to use the following I get the error "Argument not optional" within the Get property of the headCount() attribute.
Private Function PopulateTerminal()
Dim terminal As clsTerminal
Set terminal = New clsTerminal
terminal.terminalCode = "Wil"
terminal.headCount.Add "Company", 100
End Function
I assume somewhere I need to inialize the dictionary (i.e. = New Dictionary) however I am strugling with where to place it. In C# I do this in the constructor without issue, not sure what to do here.
Thanks
You can do it in the constructor of the VBA class, like so:-
Public Sub Class_Initialize()
Set myDictionary = New Dictionary
End Sub
Don't forget to always use the Set keyword when assigning an object reference, e.g.:-
Public Property Get Foo() As Dictionary
Set Foo = myDictionary
End Sub