[英]Python like inheritance for JavaScript
In python I can do something like this 在python中我可以做这样的事情
class MainClass:
def __init__(self):
self.name = "some_name"
def startDoingStuff(self):
print("I'm doing something boring")
def printName(self):
print("My name is " + self.name)
import main
class Sub(main.MainClass):
def startDoingStuff(self):
print("I'm doing something interesting")
self.name = "sub"
sub = Sub()
sub.printName() # prints 'My name is some_name'
sub.startDoingStuff()
sub.printName() # prints 'My name is sub'
Is there a JavaScript equivalent? 是否有JavaScript等价物?
If prototype-based inheritance is a little daunting, you might look into extension based inheritance . 如果基于原型的继承有点令人生畏,您可能会考虑基于扩展的继承 。
A really basic implementation looks like this. 一个非常基本的实现看起来像这样。 (John Resig's implementation linked above is more robust, but I think this is a little more readable, but with the same basic concept)
(上面链接的John Resig的实现更强大,但我认为这更具可读性,但具有相同的基本概念)
var extend = function(subTypeInit) {
var SuperType = this;
var SubType = function () {
function SuperTypeProxy(args) {
return SuperType.apply(this, args);
}
var base = new SuperTypeProxy(arguments);
subTypeInit.apply(base, arguments);
return base;
}
SubType.extend = extend.bind(SubType);
return SubType;
}
Then it can be used like this: 然后它可以像这样使用:
var Main = function (name) {
var self = this;
self.name = name;
self.doSomething = function () {
console.log("something boring");
};
self.printName = function () {
console.log("Hi, I'm "+name);
};
};
Main.extend = extend.bind(Main); //Manually attach to first parent.
var Sub = Main.extend(function () {
var self = this;
self.doSomething = function () {
console.log("something interesting");
};
var superPrintName = self.printName;
self.printName = function () {
superPrintName();
console.log("And I'm a sub class");
};
});
var sub = new Sub("foo");
sub.doSomething(); //logs "something interesting"
sub.printName(); //logs "Hi, I'm foo" "And I'm a sub class"
Some caveats here, you really probably should look into prototype based inheritance, which is what javascript is really built for. 这里有一些警告,你真的可能应该研究基于原型的继承,这正是javascript的真正构建。 Extension-based inheritance is a little more natural for someone who's used to other OO languages' approaches to inheritance, but the disadvantage is that it consumes more resources to do inheritance this way;
对于习惯于其他OO语言继承方法的人来说,基于扩展的继承更自然,但缺点是它以这种方式消耗更多资源来继承; you're creating a lot of functions (and a lot of closures), which can really add up.
你正在创建很多函数(以及很多闭包),这些函数可以真正加起来。
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