Appendix B. References for Projects

Throughout this book you have seen type libraries or object libraries, such as those described in the Automation chapter, used to enhance functionality through VBA code. You have seen how libraries can provide access to functions that manipulate the Windows System Registry or retrieve and send data to other applications.

In addition to libraries supplied with Microsoft Office, you can acquire type libraries to help simplify a variety of programming tasks. Like Microsoft Office libraries, other vendors' libraries provide classes to manipulate objects. An example would be the QuickBooks libraries provided in the QuickBooks Software Development Kit (SDK). These libraries provide classes you can use to create objects that contain data that is returned from a QuickBooks data file through an XML access method.

Acquiring libraries can be a cost-effective way to get more work done in less time. Of course there is always the trade off between what you pay for a library and writing your own functions. Not to mention the effort that may be required to learn how to use the library. And because of that trade off, you shouldn't neglect the effort you have already put into writing your own code. After all of the "bold, test, and swears" you put into your routines, you really must consider creating code libraries from your code.

This appendix describes techniques for using references to libraries in your projects, including how to reference libraries provided by others and why the order of your reference list can be important. It also discusses the types of libraries available (for example, DLLs and ActiveX Controls).

This appendix also discusses techniques for referring to the References class and why you would want to. It describes some correct techniques for writing code that will go into your own code libraries. And it suggests ways to avoid getting MISSING libraries and what to do when they go missing.