Event-driven programming is a popular technique used in programming languages like VBA to develop applications that can respond to user actions and events. In VBA, the RaiseEvent statement is a powerful tool that allows developers to raise events from within their own classes or modules. This helps in creating more robust and interactive applications.
In this blog, we will explore the purpose, syntax, examples, important notes and remarks of the VBA RaiseEvent statement and discuss its significance in event-driven programming.
VBA RaiseEvent Statement
Purpose of the VBA RaiseEvent Statement
The primary purpose of the RaiseEvent statement in VBA is to raise or trigger an event from within a class or module. It allows the developer to create custom events and handle them with the help of event handlers. This feature enables the application to respond to user actions and improve its overall functionality and user experience.
Syntax of the VBA RaiseEvent Statement
The RaiseEvent statement has the following syntax:
Here, eventname is the name of the event that is being triggered, and the argumentlist is an optional list of arguments that can be passed to the event handler. The arguments can be variables, constants, or expressions.
Examples of Using the VBA RaiseEvent Statement
Now, let’s look at the top 5 examples of how the RaiseEvent statement can be used in VBA to create custom events and handle them.
1. ‘ButtonClick’ Event Example
This example shows how the RaiseEvent statement can be used to trigger a custom ‘ButtonClick’ event when a command button is clicked.
Public Event ButtonClick()
Private Sub cmdButton_Click()
'Raise a ButtonClick event
2. ‘TextBoxChange’ Event Example
This example demonstrates how the RaiseEvent statement can be used to raise a custom ‘TextBoxChange’ event whenever the text in a text box is changed.
Public WithEvents txtBox As MSForms.TextBox
Private Sub txtBox_Change()
'Raise a TextBoxChange event
3. Custom Error Handling Example
In this example, we can use the RaiseEvent statement to trigger a custom error handling event whenever an error occurs in the code. This can be especially useful when we want to handle specific errors differently in our application.
Public Event ErrorOccurred(ErrorNumber As Long, ErrorMessage As String)
On Error GoTo errHandler
'Some code that may cause an error
'Raise an ErrorOccurred event
RaiseEvent ErrorOccurred(Err.Number, Err.Description)
4. ‘WorkbookOpen’ Event Example
We can also use the RaiseEvent statement to trigger built-in events in VBA, such as the ‘WorkbookOpen’ event. This example shows how we can raise the ‘WorkbookOpen’ event when a workbook is opened.
Private Sub Workbook_Open()
'Raise a WorkbookOpen event
5. ‘TimerTick’ Event Example
The RaiseEvent statement can also be used to handle events from external sources, such as a timer control. In this example, we can raise the ‘TimerTick’ event when the timer control’s interval is reached.
Private WithEvents tmrControl As MSForms.Timer
Private Sub UserForm_Initialize()
'Set the timer control's interval to 5 seconds
Set tmrControl = Me.Controls.Add("MSForms.Timer.1")
tmrControl.Interval = 5000
tmrControl.Enabled = True
Private Sub tmrControl_Timer()
'Raise a TimerTick event
Important Notes and Remarks
- The RaiseEvent statement can only be used within a class or module. It cannot be used in a standard module.
- The event name must match the name declared in the event declaration statement in the class or module that will handle the event.
- The event handler must be declared with the ‘Public’ access modifier in order for it to be accessible from outside the class or module.
- If no arguments are passed to the event handler, the RaiseEvent statement does not need to contain the argumentlist in its syntax.
- The RaiseEvent statement can only be used to raise events within the current project. It cannot be used to raise events in other projects.
The RaiseEvent statement in VBA is a valuable tool for event-driven programming. It allows developers to create custom events and handle them efficiently, improving the overall functionality and user experience of their applications.
In this blog, we have discussed the purpose, syntax, examples, and important notes and remarks of the RaiseEvent statement. Have you used the RaiseEvent statement in your VBA projects? What has been your experience with it? Do you have any examples that you would like to share?
We would love to hear your thoughts and feedback in the comments section below. Thank you for reading!