Page 265 - Microsoft Office Excel 2003 Programming Inside Out

Chapter 11

Creating Add-Ins and

COM Add-Ins

Introducing Add-Ins . . . . . . . . . . . . . . . . 239 Building an Automation Add-In with €
Using the Add-Ins dialog box. . . . . . . . . 240 Visual Basic 6. . . . . . . . . . . . . . . . . . . . . 250€
Creating Excel Add-Ins . . . . . . . . . . . . . 241 Building a COM Add-In with €
Using the AddIns Collection . . . . . . . . . 244 Visual Basic .NET . . . . . . . . . . . . . . . . . . 256€
Creating Automation and COM Add-Ins 247€

This chapter introduces the concept of add-ins. In this chapter, you’ll learn what an add-in is,
how to load and unload add-ins from Microsoft Excel, some common add-ins supplied with
Excel, and how to create your own Excel add-in.

Introducing Add-Ins

Add-ins allow you to extend Excel by adding commands and features to those normally found
in Excel. These commands and features can be found in many different places, including files
that were installed with Excel, the Microsoft Office Web site (http://office.microsoft.com), and
programs that you develop yourself. Once installed, an add-in works like any other menu
command or function.
There are three main types of add-ins: Excel add-ins, COM add-ins, and automation add-ins.
Excel add-ins are based on macros that are written in Microsoft Visual Basic for Applications
(VBA) and stored in a special type of workbook, called a Microsoft Office Excel Add-in, that
has a file type of .xla. COM and automation add-ins are created using a compiled language
such as Visual Basic or Visual C++.

There are two main reasons add-ins are used. First, an add-in provides a way to easily extend
the capabilities of Excel in such a way as to make it appear to the user that the capability was
originally included in Excel. This means that programmers and third-party developers can
provide easy-to-use tools that can simplify the life of the average user.

Second, add-ins don’t use any system resources until they are explicitly loaded into Excel.
This improves the overall performance of Excel for users who don’t need the extra capabilities,
while making it easy for those individuals who want the extra capabilities to access them.

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Part 4: Advanced VBA