好的代码

刚刚写代码的时候，对某个函数的调用进行了思考和修改，发现修改结果有很大的好处。把这个记录下来，努力让自己以后写代码都能这样思考。

原先的代码是这样的：

export default {
    getBoundingRect() {
                let el = this.getElement();
        let bounding = el.getBoundingClientRect();
        return {
            w: bounding.width,
            h: bounding.height,
            x: 0,
            y: 0
        }
    }
}

这段代码的作用是用户提供的重载方法，用来重载某个基础类的某个方法，这个基础类的代码基本如下：

class BaseClass {
    constructor(spec) {
         this.spec = spec;
    }

   getElement() {
        return document.body;
   }

   getBoundingRect() {  
       if (this.spec.getBoundingRect) {
            return this.spec.getBoundingRect.call(this);
       } else {
            return {};
       }
   }
}

所以当用户想要自定义getBoundingRect的行为时，可以提供一个重载的方法，即上面的代码。上面的代码是没有任何问题的，只是，考虑到代码的耦合度，还是需要修改的。

上面代码的方法中调用了基础类的一个getElement方法，也就是说这个方法依赖基础类的一个方法。那么问题来了，如果以后基础类要做一些调整，更改了getElement方法的名字，或者参数，那么所有用户的重载方法可能就都会报错了。这就是过多依赖的一个弊端。

好，既然有问题，那么就对我们的基础类做些修改，避免用户这样的使用。我们在基础类的getBoundingRect方法中，调用getElement方法，将返回值以参数的形式传给用户的重载方法。这样即使基础类的getElement方法改了，我们要做的修改仅仅限于这个类，减少了对用户自定义代码的影响。

修改后的代码：

export default {
    getBoundingRect(el) {
        let bounding = el.getBoundingClientRect();
        return {
            w: bounding.width,
            h: bounding.height,
            x: 0,
            y: 0
        }
    }
}

class BaseClass {
    constructor(spec) {
         this.spec = spec;
    }

   getElement() {
        return document.body;
   }

   getBoundingRect() {  
       let el = this.getElement();
       if (this.spec.getBoundingRect) {
            return this.spec.getBoundingRect(el);
       } else {
            return {};
       }
   }
}

Awkward moment in subway

In the subway, a girl besides me while I was waiting for next stop in the front of door. The girl seems want to get off too. She looks into the window on the door and trying to make herself look better. Arrived at the stop, the girl suddenly move to a corner and face to the wall, it seems that the girl just realized that it's not her stop.

地铁快到站的时候我站在门中间等下，然后一个女的站在我旁边，估计也是等下，然后她就对着门把门上玻璃当镜子…等到站的时候不知道她是看错站还是怎么，赶紧走到一边面朝角落去了…好尴尬

revise#1

In the subway, a girl was standing next to me while I was waiting for next stop in the front of door. The girl seems want to get off too. She looks into the window on the door and trying to make herself look better. Arrived at the stop, the girl suddenly moved to a corner and face to the wall, it seems that the girl just realized that it's not her stop.

revise#2

In the subway, a girl was standing next to me while I was waiting for the next stop in the front of the door. The girl seems to want to get off too. She looks into the window on the door and trying to make herself look better. Arrived at the stop, the girl moved to a corner and face to the wall, It seems that the girl realized that it's not her stop.

Writing good code.

  • 将容易变化的代码放到一个模块里，或者一个方法里面，给这些代码一个接口。（方便修改）
  • 将可替换的代码放到一个模块里，或者一个方法里面，给这些代码一个接口。（方便替换）
  • 将可复用的代码放到一个模块，或者一个方法里面，给这些代码一个接口。（方便复用）