Sometimes pattern descriptions can be a little tricky to understand. In this video, explore the meaning of one-to-many in the observer pattern description.
- Thinking about subscribers and publishers … is a great way to visualize the observer pattern … but if you look at the definition of the observer pattern … you'll see something like this. … The observer pattern defines a one-to-many dependency … between objects so that when one object changes state, … all its dependents … are notified and updated automatically. … Let's step through what that means. … First, the definition says that the observer pattern … defines a one-to-many relationship … between a set of objects. … We often call these objects the subject and the dependent, … which is analogous to publisher and subscriber … in our example … and we call it a one-to-many … because if the state changes in the subject, … then the many dependents are notified of that state change. … All dependent means here is that these objects … are dependent on the subject for data. … We often call the dependent the subscriber … or more commonly the observer. … The subject owns the data in the sense …
- What are design patterns?
- Encapsulating code that varies with the Strategy pattern
- The limitations of inheritance
- Using the Adapter pattern
- Implementing the Observer pattern
- Extending behavior with composition and the Decorator pattern
- Encapsulating iteration with the Iterator pattern
- Object creation with the Factory Method pattern
- Using design principles to guide your object-oriented design
Skill Level Intermediate
1. Design Patterns
2. The Strategy Pattern
3. The Adapter Pattern
4. The Observer Pattern
Using the Observer pattern2m 23s
5. The Decorator Pattern
6. The Iterator Pattern
7. The Factory Patterns
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