(window.webpackJsonp=window.webpackJsonp||[]).push([[119],{449:function(t,s,a){"use strict";a.r(s);var n=a(3),e=Object(n.a)({},(function(){var t=this,s=t._self._c;return s("ContentSlotsDistributor",{attrs:{"slot-key":t.$parent.slotKey}},[s("h1",{attrs:{id:"mixin"}},[s("a",{staticClass:"header-anchor",attrs:{href:"#mixin"}},[t._v("#")]),t._v(" Mixin")]),t._v(" "),s("p",[t._v("JavaScript 语言的设计是单一继承，即子类只能继承一个父类，不允许继承多个父类。这种设计保证了对象继承的层次结构是树状的，而不是复杂的"),s("a",{attrs:{href:"https://en.wikipedia.org/wiki/Multiple_inheritance#The_diamond_problem",target:"_blank",rel:"noopener noreferrer"}},[t._v("网状结构"),s("OutboundLink")],1),t._v("。\n"),t._v("\n但是，这大大降低了编程的灵活性。因为实际开发中，有时不可避免，子类需要继承多个父类。举例来说，“猫”可以继承“哺乳类动物”，也可以继承“宠物”。")]),t._v(" "),s("p",[t._v("各种单一继承的编程语言，有不同的多重继承解决方案。比如，Java 语言也是子类只能继承一个父类，但是还允许继承多个界面（interface），这样就间接实现了多重继承。Interface 与父类一样，也是一个类，只不过它只定义接口（method signature），不定义实现，因此又被称为“抽象类”。凡是继承于 Interface 的方法，都必须自己定义实现，否则就会报错。这样就避免了多重继承的最大问题：多个父类的同名方法的碰撞（naming collision）。")]),t._v(" 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