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book-notes/Head First Design Patterns.org

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+* Head First Design Patterns
+:PROPERTIES:
+:NOTER_DOCUMENT: ../../../pdfs/bootcamp/Head First Design Patterns.pdf
+:ID:       dc9ece84-0b14-4afd-b25a-786cf1618996
+:END:
+** Chapter 1
+:PROPERTIES:
+:NOTER_PAGE: 36
+:END:
+*** Structural:
+The Strategy Pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.
+
+- Encapsulate what varies
+
+- Favor composition over inheritance
+
+- Program to interfaces, not implementations
+  
+** Chapter 2
+:PROPERTIES:
+:NOTER_PAGE: 82
+:END:
+*** Observer:
+The Observer Pattern defines a one-to-many dependency between objects so that when
+one object changes state, all of its dependents are notified and updated automatically.
+
+Subjects, or as we also know them, Observables, update Observers using a common
+interface
+
+Observers are loosely coupled in that the Observable knows nothing about them,
+other than that they implement the Observer interface.
+
+You can push or pull data from the Observable when using the pattern (pull is
+considered more “correct”).
+
+Don’t depend on a specific order of notification for your Observers.
+
+Java has several implementations of the Observer Pattern, including the general
+purpose java.util.Observable
+
+- Strive for loosely coupled designs between objects that interact
+** Notes for page 137
+:PROPERTIES:
+:NOTER_PAGE: 137
+:END:
+
+- Classes should be open for extension, but closed for modification.
+** Notes for page 142
+:PROPERTIES:
+:NOTER_PAGE: 142
+:END:
+Notes for the decaroter pattern.
+** Notes for page 143
+:PROPERTIES:
+:NOTER_PAGE: 143
+:END:
+Decorator pattern: The Decorator Pattern attaches additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.