January 2015
Intermediate to advanced
212 pages
4h 22m
English
Content preview from Mastering Python Design PatternsBecome 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 13. The Observer Pattern
Sometimes, we want to update a group of objects when the state of another object changes. A very popular example lies in the Model-View-Controller (MVC) pattern. Assume that we are using the data of the same model in two views, for instance in a pie chart and in a spreadsheet. Whenever the model is modified, both the views need to be updated. That's the role of the Observer design pattern [Eckel08, page 213].
The Observer pattern describes a publish-subscribe relationship between a single object, : the publisher, which is also known as the subject or observable, and one or more objects, : the subscribers, also known as observers. In the MVC example, the publisher is the model and the subscribers are the views. However, ...
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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.