How to make class variables persist between modules in VBA - vba

Question

I am trying to find a way for class variables to persist between modules.
I have a use class that stores typical user data: Name, domain, manager, etc.
I'd like to store this information throughout the life of the session (while the user is using the tool), but it looks like I can't do that. Below is an example and thank for your help/advice!
JP
Here is the class module:
Private cLoggedDomain As String
Private cLoggedRole As String
Private cDepartment As String
Private cEmployeeName As String
Private cManagerName As String
Private cEmp_ID As Long
Private cEmployeeInfo As Collection
Public Property Let SetUser(value As String)
'RECIEVES THE LOGGED DOMAIN AS STRING
'GETS THE DB ATTRIBUTES FROM SQL
Set cEmployeeInfo = GetInfoFromSearch("Employee, manager, department, ety_type, emp_ID", _
"domainID = '" & value & "'", _
"Employee", "v_roster_empViewALL")
cLoggedDomain = value
cEmployeeName = cEmployeeInfo(1)(1)
cManagerName = cEmployeeInfo(1)(2)
cDepartment = cEmployeeInfo(1)(3)
cLoggedRole = cEmployeeInfo(1)(4)
cEmp_ID = cEmployeeInfo(1)(5)
End Property
Public Property Get LoggedDomain() As String
LoggedDomain = cLoggedDomain
End Property
Public Property Let LoggedDomain(value As String)
cLoggedDomain = value
End Property
Public Property Get LoggedRole() As String
LoggedRole = cLoggedRole
End Property
Public Property Get LoggedDepartment() As String
LoggedDepartment = cDepartment
End Property
Public Property Get LoggedEmployeeName() As String
LoggedEmployeeName = cEmployeeName
End Property
Public Property Get LoggedManagerName() As String
LoggedManagerName = cManagerName
End Property
Public Property Get LoggedEmpId() As String
LoggedEmpId = cEmp_ID
End Property
And the module that uses it, which works fine:
Public Sub New_LoadMain()
Dim s As Worksheet
Dim loggedUser As New cRoles
'CHECK TO SEE IF USER IS LOGGED IN
If loggedUser.LoggedDomain = "" Then
'Set loggedUser = New cRoles
loggedUser.SetUser = Environ("username")
Else
End If
Call test
However, when I try to use the test module, I get a with block error?
Sub test()
Dim test As cRoles
Dim t As String
t = test.LoggedDepartment
End Sub

Answer 1

Class modules define the public interface for objects: they are blueprints that mean nothing until they are instantiated with the New keyword.
When you do this:
Dim test As cRoles
You allocate memory for an object pointer, and telling the compiler that this object implements the cRoles interface; that's how you can type test. and get a list of all the public members on that interface.
However that object pointer points to no object: it's Nothing (literally). You need to create a new instance of that class in order to access the object test is pointing to:
Set test = New cRoles
And now accessing test members will no longer throw error 91.
Now, each instance encapsulates its own state: think of each worksheet in your workbook as a Worksheet instance: each sheet has its own separate content, but all sheets can be manipulated through the same Worksheet interface, regardless of whether you're looking at Sheet1 or Sheet42.
The same is true for all instances of your cRoles class:
Dim test1 As cRoles
Set test1 = New cRoles
test1.SetUser = user1
Dim test2 As cRoles
Set test2 = New cRoles
test2.SetUser = user2
Debug.Print test1.LoggedEmpId, test2.LoggedEmpId
The two instances are completely distinct, and each hold their own internal state. If that's what you want, then in order to create an instance in one place and consume it in another place, you'll need to pass the object reference as a parameter:
Public Sub Test()
Dim thing As cRoles
Set thing = New cRoles
thing.SetUser = Environ("username")
DoSomething thing
End Sub
Private Sub DoSomething(ByVal auth As cRoles)
Debug.Print auth.LoggedEmpId
End Sub
Note:
You typically want to pass parameters ByVal
Avoid As New since that makes an auto-instantiated object, and that comes with behavior that may or may not be expected.
You could have a global-scope Public AuthInfo As cRoles variable declared in a standard module, then a procedure responsible for creating the object and setting this global-scope reference. Then you can access AuthInfo everywhere in your VBA project - the caveat being, that global variable can now be written to by any code in your VBA project. Prefer using local variables and parameters if possible.