Page 326 - Microsoft Office Excel 2003 Programming Inside Out

Microsoft Office Excel 2003 Programming Inside Out

An object can also contain references to other objects. An order might have a reference to a
customer, or a form might contain a button. For purposes of this discussion, these object
references may also be characterized as properties.
An object can also represent a collection of similar things. For example the Employees object
could contain a collection of individual Employee objects.

Tip Adjectives Describe Nouns
You can think of objects as nouns and properties as adjectives, that is, the red flower or the
six-foot-tall person. This concept isn’t perfect because some attributes are relatively
specific, such as the truck with 55,230 miles, but this idea might be helpful as you begin
working with objects.
Chapter 14
What Are Methods?

Methods are actions that are performed by the object. For example, a report object might
include a print method that sends the report to a printer. Another way of thinking about
methods is that methods describe the operations performed with the information contained
in the properties of the object.

Tip Verbs Describe Actions
You can characterize methods as a verb that performs an operation or a task with the
properties in the object.

What Are Events?
Although not strictly a part of the object programming model, events are a useful tool that
allow an object to communicate information with the program that created the object.
Simply put, an event is a subroutine residing in the program that created the object that’s
called by the object, which is called from within the object.
An event is a useful technique that obviates the need for a program to constantly monitor an
object for changes. Instead, the object calls the event to inform the calling program of a
change in the object’s state.

Introducing Class Modules

Class modules are among the most important tools in a VBA programmer’s tool chest. A class
module allows you to create your own objects, which you can manipulate just like objects
already supplied with Microsoft Excel. And just like the objects available in Excel, a class
module can have properties, methods, and events.

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Part 4: Advanced VBA