Join Jungwoo Ryoo for an in-depth discussion in this video Observer, part of Python: Design Patterns.
- Observer establishes a one-to-many relationship between a subject and multiple observers. Our problem here is that a subject object need to be monitored, and other observer objects need to be notified when there is a change in the subject. In our scenario we need to be able keep track of core temperatures of reactors at a power plant. When there is a change in the core temperature registered observers need to be notified.
For our solution we need an abstract class called subject, which has interfaces that allow the operations, such as attaching, an observer detaching, an observer and notifying observers. We also need concrete subject classes inheriting from the abstracts subject class. Singleton is related to the observer design pattern.
- Understanding design patterns
- Best design practices: consistency, completeness, and correctness
- Working with creational patterns
- Working with structural patterns
- Working with behavioral patterns
Skill Level Intermediate
Q: In the strategy pattern example, why does the code keep executing the default function rather than the alternate?
A: The programming demonstration skips the step of defining what the strategy pattern should be when an alternate function name is provided
as an argument as shown below.
1. Understanding Design Patterns
2. Creational Patterns
3. Structural Patterns
4. Behavioral Patterns
5. Design Best Practices
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