《設計模式——可複用物件導向軟體的基礎》學習筆記（1.1）What is a design pattern?...

1.Four essential elements of a pattern:
(1)Pattern name;
(2)Problem;
(3)Solution;
(4)Consequences: The results and trade-offs of applying thepattern.


2.One person's pattern can be another person's primitive building block.


3.The design patterns in this book are descriptions of communicating objects and classes that are customized to solve a general design problem in a particular context.


4.In design with procedural laugnages, "Inheritance", "Encapsulation" and "Polymorphism" can also be design patterns.