Understanding Add-Ins

Many features of Excel are available only through what are called add-ins. For instance, the Analysis ToolPak is a good example of an add-in. The tools available in add-ins such as the Analysis ToolPak are not part of the basic Excel system, but can be added to the system as needs dictate. These add-ins are nothing more than programs which have been "added to" Excel in such a way that they appear to be part of Excel itself.

You also know that macros are nothing more than programs that you write using a language understood by Excel. These programs instruct Excel to perform tasks that otherwise might be time consuming or repetitious on your part. These programs, if elaborate enough, can become full-fledged applications that operate under Excel.

Excel allows you to translate your macro programs into add-ins, which can become part of Excel--the same as the Analysis ToolPak and others. Eventually you might want to take advantage of this capability. The files you convert to add-ins do not need to be elaborate, nor do they have to be fancy. Converting them to add-ins does have several advantages, however:

• The program code cannot be altered by others.
• The program code runs a bit quicker.
• The add-in is available without needing to open any particular workbook.
The functions provided by the add-in appear to be a part of Excel.

In essence, add-ins are nothing but a special type of workbook which you have converted to an add-in format that is understood by Excel.

You may want to make sure your macro code which is destined to be an add-in performs some initializing routine that modifies, in some way, the Excel user interface. For instance, most add-ins modify the menu structure in some way so that the functions in the add-in can be accessed. Your macros should take care of the menu modification so that people can access your add-ins. If you don't modify the interface in some way, then users can only get to the macro code in your add-in by directly referencing in a worksheet formula the names of any functions in your add-in.