Class Module Level

This example shows you how to create a class that contains a user defined event.
This requires three components.
ClassToRaiseEvent - This is a class module that contains an object that raises a user defined event.
ClassToHandleEvent - This is a class module that contains the code that handles the event.
Module1 - This is a standard module that contains the code that creates the two classes and calls the corresponding method.


Class Module - ClassToRaiseEvent

Often referred to as the Provider.
Create a new class module called "ClassToRaiseEvent".
Declare the event that you want to be raised using the Event keyword. In this example the event is called "MyTextChangedEvent".

Public Event MyTextChangedEvent(ByVal myString As String) 

Create an internal field called "MyField".
This field will be used to hold a text string (inside the object/class).

Private myField As String 

Create a Method called "Method_SetText".
This method will assign a text string to that field and use the keyword "RaiseEvent" to trigger the MyTextChangedEvent event.
This event will be raised every time the method is called.

Public Function Method_SetText(ByVal myString As String) 
    myField = myString
    RaiseEvent MyTextChangedEvent(myString)
End Function

Class Module - ClassToHandleEvent

Often referred to as the Client.
Create a new class module called "ClassToHandleEvent".
Define a variable that has the type "ClassWithAnEvent" and add the WithEvents keyword, to indicate that this instance can raise events.

Public WithEvents myEvents As ClassToRaiseEvent 

Once the WithEvents variable has been declared this object will appear in the top left drop-down.
Create an event handler for the MyTextChangedEvent.

Private Sub myEvents_MyTextChangedEvent(ByVal myString As String) 
    Debug.Print myString
End Sub

Standard Module - Module1

Create a new standard module called "Module1".
Declare a subroutine called "Example".
Declare a variable of type "ClassToRaiseEvent".
Create a new instance of this object and assign it to a variable called "class_raise".

Dim class_raise As ClassToRaiseEvent 
Set class_raise = New ClassToRaiseEvent

Declare a variable of type "ClassToHandleEvent".
Create a new instance of this object and assign it to a variable called "class_handle".
Assign the myEvents variable to the new "ClassToRaiseEvent" variable.

Dim class_handle As ClassToHandleEvent 
Set class_handle = New ClassToHandleEvent
Set class_handle.myEvents = class_raise

Call the method (3 times) that changes the text string and triggers the event.

Public Sub Example() 
    Dim class_raise As ClassToRaiseEvent
    Set class_raise = New ClassToRaiseEvent
    
    Dim class_handle As ClassToHandleEvent
    Set class_handle = New ClassToHandleEvent
    Set class_handle.myEvents = class_raise

    Call class_raise.Method_SetText("text 1")
    Call class_raise.Method_SetText("text 2")
    Call class_raise.Method_SetText("text 3")
End Sub

Select (Debug > Compile) and then run the subroutine.
Display the Immediate window to see the Debug.Print entries.


© 2021 Better Solutions Limited. All Rights Reserved. © 2021 Better Solutions Limited TopPrevNext