December 2015
Beginner to intermediate
195 pages
2h 52m
English
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CHAPTER 23
Visitor Patterns
GoF Definition: Represent an operation to be performed on the elements of an object structure. The visitor pattern lets you define a new operation without changing the classes of the elements on which it operates.
Concept
This pattern helps us to add new functionalities to an existing object structure in such a way that the old structure remains unaffected by these changes. So, we can follow the open/close principle here (i.e., extension allowed but modification disallowed for entities like class, function, modules, etc.).
Real-Life Example
Consider a taxi booking scenario. The taxi arrives at our defined location for ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.