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Chapter 1: A Quick Introduction to Programming
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Else
Greeting = “Hello, “ & YourName & “, great to meet you.”
If YourName = “Fred” Then
Greeting = Greeting & “ Nice to see you Fred.”
End If
End If
MsgBox Greeting
PromptUserName = YourName
End Function
As you can see, calling the PromptUserName function is pretty straightforward. Once you have written
a procedure, calling it is no different than calling a built-in VBScript procedure.
Advantages to Using Procedures
Procedures afford several key advantages that are beyond the scope of this discussion. However, here
are a few of the most important ones:
❑ Code such as that put in the PromptUserName function can be thought of as “generic,” meaning
that it can be applied to a variety of uses. Once you have created a discreet, well-defined, generic
function such as
PromptUserName , you are free to reuse it any time you want to prompt users
for their name. Once you’ve written a well-tested procedure, you never have to write that code
again. Any time you need it, you just call the procedure. This is known as code reuse.
❑ When you call a procedure to perform a task rather than writing the code in-line, it makes that
code much easier to read and maintain. Increasing the readability, and therefore the manageability
and maintainability, of your code is a good enough reason to break a block of code out into its
own procedure.
❑ When code is isolated into its own procedure, it greatly reduces the effects of changes to that
code. This goes back to the idea of the black box. As long as the procedure maintains its
predictable inputs and outputs, changes to the code inside of a procedure are insulated from
harming the code that calls the procedure. You can make significant changes to the procedure,
but as long as the inputs and outputs are predictable and remain unchanged, the code will
work just fine.
Top-Down versus Event-Driven
Before you leave this introduction to programming, it may be helpful to point out that you will encounter
two different models of programming in this book: top-down and event-driven programs. The differences
between the two have to do with the way you organize your code and how and when that code gets
executed at runtime. As you get deeper into programming in general, and VBScript in particular, this will
become clearer, so don’t be alarmed if it doesn’t completely sink in right now.
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