Visual Basic 2005 in a Nutshell, Third Edition

The Structure of a Visual Basic Program | 97

Program

Structure

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Calling Routines from Event Handlers

Once processing has been directed to one of your event handlers, it’s time to do

some work. Of course, you can write every bit of processing code right there in

the event-handling routine, but for readability, a divide-and-conquer approach

often works better. An event handler can call methods, functions, and proce-

dures, and can set and retrieve property values, all from classes in your own

application or from the .NET Framework Class Library. In Example 6-3, the

SaveAllData command button’s Click event demonstrates this approach to event

handling by calling

SaveDetails, a method in some other part of the code, to do

most of the work.

The

SaveDetails method contains all the code to actually save the details, and it

can be called from anywhere in the class (or from other classes, if it is public).

Placing code in custom procedures not only improves readability of the code, it

centralizes the work, making it possible to use the same collection of source code

statements from multiple places in your application.

Writing Custom Procedures

Custom procedures can be added to any class, structure, or module in your appli-

cation. Visual Basic includes three main types of custom procedures or routines: ...