Specifying Load Behavior
When a COM add-in has been properly registered, it is available to whatever applications are specified in the add-in designers that the project contains. The registered COM add-in display name appears in the COM Add-in dialog box; if it does not, click Add to browse for the add-in and add it to the list.
Selecting the check box next to an add-in in the COM Add-ins dialog box loads (connects) the add-in and makes it available to the user; clearing the check box unloads (disconnects) the add-in, and it cannot be run.
As the developer, you specify the default setting for when a COM add-in should be loaded. You do this in the Initial Load Behavior list in the add-in designer.
**Note **Users can change this setting later by using the Add-in Manager.
You can specify that an add-in be loaded in one of the following ways:
- Only when the user loads it in the COM Add-ins dialog box, or when Microsoft® Visual Basic® for Applications (VBA) code loads it by setting the Connect property of the corresponding COMAddIn object.
- Every time the application starts.
- The first time the application starts, so that it can create a toolbar button or menu item for itself. After that, the add-in is loaded only when the user requests it by clicking the menu item or button.
The following table describes the different settings for the Initial Load Behavior setting.
| Initial Load Behavior setting | Behavior |
|---|---|
| None | The COM add-in is not loaded when the application boots. It can be loaded in the COM Add-ins dialog box or by setting the Connect property of the corresponding COMAddIn object. |
| Startup | The add-in is loaded when the application boots. When the add-in is loaded, it remains loaded until it is explicitly unloaded. |
| Load on Demand 1 | The add-in is not loaded until the user clicks the button or menu item that loads the add-in, or until a procedure sets its Connect property to True. In most cases, you will not set the initial load behavior to Load on Demand directly; you will set it to Load at Next Startup Only, and it will be set automatically to Load on Demand on subsequent boots of the host application. |
| Load at Next Startup Only 1 | After the COM add-in has been registered, it loads as soon as the user runs the host application for the first time. The next time the user boots the application, the add-in is loaded on demand — that is, it does not load until the user clicks the button or menu item associated with the add-in, or through the COM Add-in dialog box. |
| Command line/Startup | Add-in loads either when specifically invoked from a command-line parameter, when Visual Basic starts. |
| Command line | Add-in loads only when specifically invoked from a command-line parameter. |
1 Not available to add-ins developed using VBA.
See Also
Building COM Add-ins for Office Applications | Working with Add-in Designers | Writing Code in the Add-in Designer | Hooking a COM Add-in Up to a Command Bar Control | Debugging a COM Add-in | Making the DLL | Distributing COM Add-ins | COM Add-ins and Security