TypeScript 原型模式讲解和代码示例
原型是一种创建型设计模式， 使你能够复制对象， 甚至是复杂对象， 而又无需使代码依赖它们所属的类。
所有的原型类都必须有一个通用的接口， 使得即使在对象所属的具体类未知的情况下也能复制对象。 原型对象可以生成自身的完整副本， 因为相同类的对象可以相互访问对方的私有成员变量。
复杂度：
流行度：
使用示例： TypeScript 的 Cloneable （克隆） 接口就是立即可用的原型模式。
识别方法： 原型可以简单地通过 clone或 copy等方法来识别。
概念示例
本例说明了原型设计模式的结构并重点回答了下面的问题：
- 它由哪些类组成？
- 这些类扮演了哪些角色？
- 模式中的各个元素会以何种方式相互关联？
index.ts: 概念示例
/** * The example class that has cloning ability. We'll see how the values of field * with different types will be cloned. */ class Prototype { public primitive: any; public component: object; public circularReference: ComponentWithBackReference; public clone(): this { const clone = Object.create(this); clone.component = Object.create(this.component); // Cloning an object that has a nested object with backreference // requires special treatment. After the cloning is completed, the // nested object should point to the cloned object, instead of the // original object. Spread operator can be handy for this case. clone.circularReference = new ComponentWithBackReference(clone); return clone; } } class ComponentWithBackReference { public prototype; constructor(prototype: Prototype) { this.prototype = prototype; } } /** * The client code. */ function clientCode() { const p1 = new Prototype(); p1.primitive = 245; p1.component = new Date(); p1.circularReference = new ComponentWithBackReference(p1); const p2 = p1.clone(); if (p1.primitive === p2.primitive) { console.log('Primitive field values have been carried over to a clone. Yay!'); } else { console.log('Primitive field values have not been copied. Booo!'); } if (p1.component === p2.component) { console.log('Simple component has not been cloned. Booo!'); } else { console.log('Simple component has been cloned. Yay!'); } if (p1.circularReference === p2.circularReference) { console.log('Component with back reference has not been cloned. Booo!'); } else { console.log('Component with back reference has been cloned. Yay!'); } if (p1.circularReference.prototype === p2.circularReference.prototype) { console.log('Component with back reference is linked to original object. Booo!'); } else { console.log('Component with back reference is linked to the clone. Yay!'); } } clientCode(); Output.txt: 执行结果
Primitive field values have been carried over to a clone. Yay! Simple component has been cloned. Yay! Component with back reference has been cloned. Yay! Component with back reference is linked to the clone. Yay! 
