November 2001
Intermediate to advanced
512 pages
9h 10m
English
Content preview from Visual Basic Design Patterns: VB 6.0 and VB.NETBecome an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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Chapter 32. The Visitor Pattern
The Visitor pattern turns the tables on our object-oriented model and creates an external class to act on data in other classes. This is useful when you have a polymorphic operation that cannot reside in the class hierarchy for some reason—for example, because the operation wasn't considered when the hierarchy was designed or it would clutter the interface of the classes unnecessarily. The Visitor pattern is easier to explain using VB7, since polymorphism and inheritance make the code rather simpler. We'll discuss how to implement the Visitor in VB6 at the end of this chapter.
Motivation
While at first it may seem “unclean” to put operations inside one class that should be in another, there are good reasons for doing ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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