摘要：Here are some common causes of redesign along with the design pattern(s) that address them:Creating an object by specifying a class explicitly.通过显示方式指定一个类来创建对象在创建对象时指定类名将使你受特定实现的约束，而不是特定接口的约束。Abstract Factory(87) ,Factory Method(107),Prototype(117)Dependence on specific operations.对特殊操作的依赖当你为请求指定一个特 阅读全文

摘要：e = 阅读全文

摘要：初等函数是由幂函数(power function)、指数函数(exponential function)、对数函数(logarithmicfunction)、三角函数(trigonometric function)、反三角函数(inverse trigonometic function)与常数经过有限次的有理运算（加、减、乘、除、有理数次乘方、有理数次开方）及有限次函数复合所产生、并且能用一个解析式表示的函数。 阅读全文

摘要：In contrast, an object's type only refers to its interface--the set of requests to which it can respond.An object can have many types,and objects of different classes can have the same type.Creational patterns ensure that your system is written in terms of interfaces,not implementions.principle 阅读全文