Visual Basic Modules and Procedures

A key part of developing applications using Visual Basic is ensuring that the code is carefully structured. This involves segmenting the code into projects, modules and procedures so that it is easy to understand and maintain.

A complete Visual Basic application is typically contained in a single project. Within a project, code is placed in separate code files called modules, and within each module, the Visual Basic code is further separated into self contained and re-usable procedures.

The topic of projects was covered in Creating a New Visual Basic Project. In this chapter we will look in detail at Visual Basic modules and procedures.

Visual Basic application source code is structured into module files with .vb suffix. By default, Visual Studio creates a separate module file for each form in an application containing the code to construct the form and any code that has been defined by the developer in the event procedures.

When writing additional Visual Basic for an application the code should ideally be logically grouped to together with other source code in a module file. When we say logically grouped we mean that the code shopuld be grouped with other code of a similar nature. For example, code to work with files might be placed in a module called FileIO.vb, while mathematical procedures might all reside in a file name Math.vb. The idea is to ensure Visual Basic code is placed in a file where it make sense for it to be located. This will differ between applications, but it is worth investing the time to ensure code is well structured as doing so makes subsequent maintenance of the code by you or other developers much easier.

We mentioned previously that Visual Studio places the code to construct each form in a separate module file. We now need to learn how to create a new module in a project to ocntian our own Visual Basic code.