You want to be able to extend a design to accommodate change, but how? This video walks you through how the decorator pattern can help.
- [Instructor] Before we jump into a formal definition … of the Decorator pattern, let's first get … a conceptual feel for how Decorator works … and in particular see how we might use composition … to solve our problems. … To do that, let's go back to our original beverage design. … Now, let's say a customer wants to order DarkRoast … with Mocha and Whip. … So, let's start simply by instantiating … a DarkRoast object, shown here. … Let's also call this object our base object, … the coffee itself. … Next, the customer wants Mocha, so let's create … a second object, a Mocha object and wrap it around … or compose it with the DarkRoast object. … We'll call Mocha a Decorator and as to the hint … to the structure of all this, Mocha's type … is going to mirror the type of the object … that it's composed with. … Which, in this case, is a beverage. … So, Mocha also has type beverage. … Note that means it also has a cost method, … so keep that in mind. … Now the customer also wants Whip, … so let's create a Whip object and wrap it around …
- 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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