Using classes instead of global variables in vba - vba

Excel VBA won't let you use global variables of arrays so I am trying to use a class to keep track of the variables I need. I am trying to create the variable in one sub and call it from another, but I don't know how to do it.
Sub Test3()
Dim mc As cVars
Set mc = New cVars
Dim ex() As Double
ReDim ex(1 To 5)
For i = 1 To 5
ex(i) = i
Next i
mc.Arr = ex
Call Test4
End Sub
Sub Test4()
Dim out() As Double
ReDim out(1 To 5)
out = mc.Arr
MsgBox (out(2))
End Sub
...
Option Explicit
Private pArr() As Double
Public Property Get Arr() As Double()
Arr = pArr()
End Property
Public Property Let Arr(p() As Double)
pArr = p()
End Property
The error comes in Test4() because there is no mc initiated, I tried initiating it but it then is not the same class (I believe)

Why not change Sub Test4() to a function instead calling a variable mc:
Function Test4(mc As cVars)
Dim out() As Double
ReDim out(1 To 5)
out. mc.Arr
MsgBox(out(2))
End Function
That may work.

Related

Can-I assign a value directly to an object?

In VBA, you can use either Cells or Cells.Value, it has the same effect. Test1 and Test2 behaves the same way, allthough in test 2 the string is passed directly to the object.
Sub Test1()
Cells(1, 1) .Value = "Hello"
End Sub
Sub Test2()
Cells(1, 2) = "World"
End Sub
Is it possible to do something similar with any user class? Can-I assign a value directly to an object created from one of my classes withpout using the property value ?
Following Tim and K. recommendations, I've created a the following class:
Option Explicit
Dim LNG_Debut As Long
Public Property Let Debut(tLNG_Debut As Long)
LNG_Debut = tLNG_Debut
End Property
Property Get Debut() As Long
Debut = LNG_Debut
End Property
Then, I’ve exported that class to notepad and modified it the following way:
Property Get Debut() As Long
Attribute Debut.VB_UserMemId = 0
Debut = LNG_Debut
End Property
And finaly, I’ve imported it back in the VBA editor.
Then, both Test1 and Test2 have the same result
Sub Test1()
Dim MyVariable As obj_Test
Set MyVariable = New obj_Test
MyVariable.Debut = 10
End Sub
And
Sub Test2()
Dim MyVariable As obj_Test
Set MyVariable = New obj_Test
MyVariable = 10
End Sub
Many thanks

Assigning Entire Private Array via class properties

I have an array that is a fixed size as a Private variable for one of my classes. Is there a way to set up a get/let property that will allow me to pass the entire array to the object, or will I have to assign the values independently? What about with a public function?
I am not sure but maybe you are talking about sth like that.
A class with the name cArray
Option Explicit
Dim mArr(1 To 5) As String
Property Get aValue() as Variant
aValue = mArr
End Property
Private Sub Class_Initialize()
mArr(1) = "Test1"
mArr(2) = "Test2"
mArr(3) = "Test3"
mArr(4) = "Test4"
mArr(5) = "Test5"
End Sub`
And for testing
Option Explicit
Sub Test()
Dim c As cArray
Dim v As Variant
Dim i As Long
Set c = New cArray
v = c.aValue
For i = LBound(v) To UBound(v)
Debug.Print v(i)
Next i
End Sub
Update: for the let part you will need a loop
Property Let aValue(nVal As Variant)
Dim i As Long
For i = LBound(nVal) To UBound(nVal)
mArr(i) = nVal(i)
Next i
End Property

Variant array is 'corrupted' when running macro - Excel crashes

I have a macro (code attached) which writes the data from two sheets into two variant arrays. It then uses a nested loop to look for all possible matches in the 2nd sheet on a piece of data in the 1st sheet.
When the first match is found one of the variant arrays appears to get wiped and I get a 'Subscript out of range'. this can happen when the data is being compared or when I subsequently try to pass data from that array to another procedure as a result of a match being found.
When I look in the Locals window, this array can change from showing the stored values to having the error message "Application-defined or object-defined error" in each index, or no indexes at all, or indexes with high negative numbers.
Regardless, if I try to investigate further while the code is in debug mode, Excel crashes ("Excel has encountered a problem and needs to close").
I have followed the advice at this link:
http://exceleratorbi.com.au/excel-keeps-crashing-check-your-vba-code/
...but to no avail.
I've stepped through the code and can trace it to the first time the data values being tested match. It happens for the same indexes (same i and j values) every time I run.
I'm using Excel 2013 on our office network.
Can anyone tell me what might be causing this or any tests I could perform to help narrow down the cause?
Could it be due to memory use? The arrays come out at about 15000 x 11 and 4000 x 6 and it's the smaller one that is being corrupted/failing.
Sub classTest()
Dim i As Long, j As Long
Dim CK_Array() As Variant, RL_Array() As Variant
Dim wb As Workbook
Dim CK_Data As Worksheet, RL_Data As Worksheet
Set wb = ThisWorkbook
Set CK_Data = wb.Sheets(1)
Set RL_Data = wb.Sheets(2)
Call getRange_BuildArray(CK_Array, CK_Data)
Call getRange_BuildArray(RL_Array, RL_Data) ' this sets the array that gets corrupted.
For i = 2 To UBound(CK_Array)
If Not IsEmpty(CK_Array(i, 6)) Then
For j = 2 To UBound(RL_Array)
If CK_Array(i, 6) = RL_Array(j, 4) Then ' array gets corrupted here or line below
Call matchFound(dResults, CStr(CK_Array(i, 1) & " | " & CK_Array(i, 5)), CStr(RL_Array(j, 2) & " " & RL_Array(j, 3)), CStr(RL_Array(j, 1)), CStr(RL_Array(1, 3))) ' or array gets corrupted here
End If
Next j
End If
Next i
End Sub
Private Sub getRange_BuildArray(arr As Variant, ws As Worksheet)
Dim endR As Long, endC As Long
Dim rng As Range
endR = ws.UsedRange.Rows.Count
endC = ws.UsedRange.Columns.Count
Set rng = Range(ws.Cells(1, 1), ws.Cells(endR, endC))
arr = rng
End Sub
EDIT:
As requested here is the code to the matchfound Sub. It's a dictionary, which holds class objects in a collection. Therefore I have also posted the class code below. I'm not yet making use of all of the class properties and methods as this issue has halted my testing.
Sub matchFound(dictionary As Object, nameCK As String, nameRL As String, RLID As String, dataitem As String)
Dim cPeople As Collection
Dim matchResult As CmatchPerson
If dictionary.exists(nameCK) Then
Set matchResult = New CmatchPerson
matchResult.Name = nameRL
matchResult.RLID = RLID
matchResult.matchedOn = dataitem
dictionary.Item(nameCK).Add matchResult
Else
Set cPeople = New Collection
Set matchResult = New CmatchPerson
matchResult.Name = nameRL
matchResult.RLID = RLID
matchResult.matchedOn = dataitem
cPeople.Add matchResult
dictionary.Add nameCK, cPeople
End If
End Sub
Class
Option Explicit
Private pName As String
Private pRLID As String
Private pMatchedOn As String
Public Property Get Name() As String
Name = pName
End Property
Public Property Let Name(Name As String)
pName = Name
End Property
Public Property Get RLID() As String
RLID = pRLID
End Property
Public Property Let RLID(ID As String)
pRLID = ID
End Property
Public Property Get matchedOn() As String
matchedOn = pMatchedOn
End Property
Public Property Let matchedOn(textString As String)
pMatchedOn = textString
End Property
Public Sub MatchedOnString(datafield As String)
Dim text As String
text = Me.matchedOn & "|" & datafield
Me.Name = text
End Sub
I've reduced your problem to a Minimum, Verifiable and Complete Example.
The problem occurs when you assign the implicit default value of a range to a Variant variable that was passed as a Variant array.
Sub VariantArrayWTF()
Dim aBar() As Variant
Dim aFoo() As Variant
GetArray aBar
GetArray aFoo
Debug.Print aBar(1, 1)
'aFoo() has now lost it's `+` sign in Locals window, but the bounds are still visible
Debug.Print aBar(1, 1)
'aFoo() has now lost its bounds in Locals Window
'aFoo(1,1) will produce subscript out of range
'Exploring the Locals Window, incpsecting variables, will crash Excel
Debug.Print aFoo(1, 1)
End Sub
Sub GetArray(ByRef theArray As Variant)
'Note the use of theArray instead of theArray()
'Implicitly calling the default member is problematic
theArray = Sheet1.UsedRange
End Sub
There are a number of workarounds - I'd recommend using both:
Use Explicit calls to `Range.Value`
You can even make explicit call to the default member Range.[_Default]. The exact method isn't important, but it must be explicit.
Sub GetArray(ByRef theArray As Variant)
theArray = Sheet1.UsedRange.Value
End Sub
Avoid the use of `Call`, and pass common Variant definitions
Call is a deprecated statement, and can be omitted.
Declare the arrays and the helper functions' array argument consistently. That is, use () in all instances, or none.
Note the difference between declaring Dim aFoo() As Variant which is an array of Variants, and declaring Dim aFoo As Variant which is a Variant that can contain an array.
With Parentheses
Sub VariantArrayWTF()
Dim aBar() As Variant
Dim aFoo() As Variant
GetArray aBar
GetArray aFoo
Debug.Print aBar(1, 1)
Debug.Print aBar(1, 1)
Debug.Print aFoo(1, 1)
End Sub
Sub GetArray(ByRef theArray() As Variant)
theArray = Sheet1.UsedRange
End Sub
Without Parentheses
Sub VariantArrayWTF()
Dim aBar As Variant
Dim aFoo As Variant
GetArray aBar
GetArray aFoo
Debug.Print aBar(1, 1)
Debug.Print aBar(1, 1)
Debug.Print aFoo(1, 1)
End Sub
Sub GetArray(ByRef theArray As Variant)
theArray = Sheet1.UsedRange
End Sub
I have found the lines of code which were causing the problem. However, I cannot explain why it would necessarily cause a crash so I would appreciate other input on why this is happening.
When passing the RL and CK arrays to the getRange_Build Array sub I left out the brackets that would have denoted these variables as arrays.
The code was this...
Call getRange_BuildArray(CK_Array, CK_Data)
Call getRange_BuildArray(RL_Array, RL_Data)
...but should have been this
Call getRange_BuildArray(CK_Array(), CK_Data)
Call getRange_BuildArray(RL_Array(), RL_Data)
I'm thinking the reason that this didn't get flagged as a compile error is because the parameter in question in the getRange_BuildArray procedure itself also lacked the necessary brackets to denote an array.
It was this...
Private Sub getRange_BuildArray(arr As Variant, ws As Worksheet)
...it should have been this
Private Sub getRange_BuildArray(arr() As Variant, ws As Worksheet)
With those changes in place the macro is completing successfully for the full dataset and is not causing excel to crash.
As mentioned it would be great if someone could offer a more detailed breakdown of how this caused excel to crash.

How do I declare a constant variable with a value of a function call

In a VBA module I have the following declaration of constants:
Private Const const_abc = 3000
Private Const const_def = 900
Private Const const_etc = 42
' and so on and so forth
Now, I have to initialize these values with a one time function call, ideally something like so
Private Const const_abc = someFunc(18)
Private Const const_def = someFunc( 7)
Private Const const_etc = someFunc( 5)
' and so on and so forth
Of course, this won't work in VBA. So, is there a common pattern on how to deal with such a requirement?
I probably could go like so
Private const_abc As Double
Private const_def As Double
Private const_etc As Double
sub initConsts()
const_abc = someFunc(18)
const_def = someFunc( 7)
const_etc = someFunc( 5)
end sub
But then I'd have to make sure that initConsts is called which I'd rather not do.
Edit As per the question of S O, I am using MS-Access.
Create a class that reads the cell and presents a Get-only interface to the value.
Here's a class called ItsMyValueClass
Option Explicit
Private pMyVal As Integer
Public Property Get MyValue() As Integer
MyValue = pMyVal
End Property
Private Sub class_initialize()
'pMyVal = Sheet.Range("somewhere)
pMyVal = 17
End Sub
And here's the code in your module:
Option Explicit
Sub IsItReadOnly()
Dim valu As ItsMyValueClass
Dim x As Integer
Set valu = New ItsMyValueClass
x = valu.MyValue
'valu.MyValue = 23 'compile error "Can't assign to read-only property"
End Sub
Public Function White() as Long
White = RGB(255,255,255)
End function
Private Sub TestIt()
Debug.Print "White is " & White
White = 123 ' <-- compile error
End Sub
in a one-liner that works with modules and classes alike for pure constant-like access:
Public Property Get myConst() As Integer: myConst = 3: End Property
you would use it like this:
Sub test()
Debug.Print "myConst: " & myConst 'would print: "myConst: 3"
End Sub
and if it has to be initialized with a custom value once, one could do it with a static property and one or many private variables:
Private ci As Boolean 'constants initialized
Private myConst1_ As Integer
Private myConst2_ As Integer
Static Property Get myConst1() As Integer
If Not ci Then init
myConst1 = myConst1_
End Property
Static Property Get myConst2() As Integer
If Not ci Then init
myConst2 = myConst2_
End Property
Private Sub init()
'these can come from anywhere:
myConst1_ = 3
myConst2_ = 5
ci = True
End Sub
they are initialized on the first access of the first "constant" property
if you have to initialize them earlier one could just call the init function earlier (and optionally remove the ci variable and all related lines if it is ensured that the properties are not accessed earlier)

Extend Collections Class VBA

I have created a sort function to allow a collection of instances of a custom object to be sorted based on one of the objects properties. Is it possible to extend the existing collections class in VBA? I do not believe inheritance is supported in VBA, so I am not sure how to go about this in the proper way. I could just create a new module and place the function in that module, but that doesn't seem like the best way of doing it.
Thanks for the responses. I ended up creating my own class which extends the Collections class in VBA. Below is the code if anyone is interested.
'Custom collections class is based on the Collections class, this class extendes that
'functionallity so that the sort method for a collection of objects is part of
'the class.
'One note on this class is that in order to make this work in VBA, the Attribute method has to be added
'manually. To do this, create the class, then export it out of the project. Open in a text editor and
'add this line Attribute Item.VB_UserMemId = 0 under the Item() function and this line
'Attribute NewEnum.VB_UserMemId = -4 under the NewEnum() function. Save and import back into project.
'This allows the Procedure Attribute to be recognized.
Option Explicit
Private pCollection As Collection
Private Sub Class_Initialize()
Set pCollection = New Collection
End Sub
Private Sub Class_Terminate()
Set pCollection = Nothing
End Sub
Function NewEnum() As IUnknown
Set NewEnum = pCollection.[_NewEnum]
End Function
Public Function Count() As Long
Count = pCollection.Count
End Function
Public Function item(key As Variant) As clsCustomCollection
item = pCollection(key)
End Function
'Implements a selection sort algorithm, could likely be improved, but meets the current need.
Public Sub SortByProperty(sortPropertyName As String, sortAscending As Boolean)
Dim item As Object
Dim i As Long
Dim j As Long
Dim minIndex As Long
Dim minValue As Variant
Dim testValue As Variant
Dim swapValues As Boolean
Dim sKey As String
For i = 1 To pCollection.Count - 1
Set item = pCollection(i)
minValue = CallByName(item, sortPropertyName, VbGet)
minIndex = i
For j = i + 1 To pCollection.Count
Set item = pCollection(j)
testValue = CallByName(item, sortPropertyName, VbGet)
If (sortAscending) Then
swapValues = (testValue < minValue)
Else
swapValues = (testValue > minValue)
End If
If (swapValues) Then
minValue = testValue
minIndex = j
End If
Set item = Nothing
Next j
If (minIndex <> i) Then
Set item = pCollection(minIndex)
pCollection.Remove minIndex
pCollection.Add item, , i
Set item = Nothing
End If
Set item = Nothing
Next i
End Sub
Public Sub Add(value As Variant, key As Variant)
pCollection.Add value, key
End Sub
Public Sub Remove(key As Variant)
pCollection.Remove key
End Sub
Public Sub Clear()
Set m_PrivateCollection = New Collection
End Sub
One popular option is to use an ADO disconnected recordset as a sort of hyperpowered collection/dictionary object, which has built-in support for Sort. Although you are using ADO, you don't need a database.
I would create a wrapper class that exposes the collection object's properties, substituting the sort function with your own.