Documenting the development effort

Putting a spreadsheet application together is one thing. Making it understandable for other people is another. As with traditional programming, it's important that you thoroughly document your work. Such documentation helps you if you need to go back to it (and you will), and it helps anyone else whom you might pass it on to.

Tip You might want to consider a couple of things when you document your project. For example, if you were hired to develop an Excel application, you might not want to share all your hard-earned secrets by thoroughly documenting everything. If this is the case, you should maintain two versions: one thoroughly documented (for your own reference) and the other partially documented (for other users).

How do you document a workbook application? You can either store the information in a worksheet or use another file. You can even use a paper document if you prefer. Perhaps the easiest way is to use a separate worksheet to store your comments and key information for the project. For VBA code, use comments liberally. (VBA text preceded with an apostrophe is ignored because that text is designated a comment.) Although an elegant piece of VBA code can seem perfectly obvious to you today, when you come back to it in a few months, your reasoning might be completely obscured unless you use the VBA comment feature.

Why Is There No Runtime Version of Excel?

When you distribute your application, you need to be sure that each end user has a licensed copy of the appropriate version of Excel. It's illegal to distribute a copy of Excel along with your application. Why, you might ask, doesn't Microsoft provide a runtime version of Excel? A runtime version is an executable program that can load files but not create them. With a runtime version, the end user wouldn't need a copy of Excel to run your application. (This is common with database programs.)

I've never seen a clear or convincing reason why Microsoft does not have a runtime version of Excel, and no other spreadsheet manufacturer offers a runtime version of its product, either. The most likely reason is that spreadsheet vendors fear that doing so would reduce sales of the software. Or, it could be that developing a runtime version would require a tremendous amount of programming that would just never pay off.

On a related note ... Microsoft does offer an Excel file viewer. This product lets you view Excel files if you don't own a copy of Excel. Macros, however, will not execute. You can get a copy of this free file viewer from the Microsoft Web site (http://www.office.microsoft.com/downloads)._

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