Microsoft Office

Creating Custom Excel
Add-Ins
For developers, one of the most useful features in Excel is the capability to
create add-ins. This chapter discusses this concept and provides a practical
example of creating an add-in.
What Is an Add-In?
IN THIS CHAPTER
Understanding add-ins
Converting a workbook to an
add-in
Generally speaking, an add-in is something that’s added to software to give it
additional functionality. Excel includes several add-ins, including the Analysis
ToolPak and Solver. Some add-ins (the Analysis ToolPak, discussed in Chapter
38, is one example) provide new worksheet functions that you can use in formulas.
Ideally, the new features blend in well with the original interface so that they
appear to be part of the program.
Excel’s approach to add-ins is quite powerful because any knowledgeable Excel
user can create add-ins from workbooks. An Excel add-in is basically a different
form of a workbook file. Any Excel workbook can be converted into an add-in,
but not every workbook is a good candidate for an add-in.
What distinguishes an add-in form a normal workbook? Add-ins, by default,
have an .xlam extension In addition, add-ins are always hidden, so you can’t display
worksheets or chart sheets that are contained in an add-in. But, you can
access its VBA procedures and display dialog boxes that are contained on
UserForms.
The following are some typical uses for Excel add-ins:
n
n
To store one or more custom worksheet functions. When
the add-in is loaded, you can use the functions like any
built-in worksheet function.
To store Excel utilities. VBA is ideal for creating
general-purpose utilities that extend the power of Excel.
The Power Utility Pak that I created is an example.
771