寻找一种重构D3.js风格方法链模式的方法

问题描述

在学习D3.js时，我遇到了，介绍了主要设计 - 模式后面是可重用的代码单元。我已经复制了下面的相关位代码。下面提供的模式的方式正是它在D3代码库和插件中使用的方式（）。

While learning D3.js, I have come across the blog post explaining the main design-pattern behind it's reusable units of code. I have reproduced the relevant bit of code below. The way the pattern is presented below is exactly the way it is used in D3 codebase and plug-ins (example).

我的一个问题是，它有这么多的属性的复制粘贴。 JavaScript是一个功能语言，我想我可以重新考虑样板代码，但我不能想到一个办法。 如果您定义 getSet ，则只有一个地方。

There is still some boilerplate for the call, but at least the logic is centralized and can be updated in only one place, if needed.

推荐答案

图表的范围，它也可以访问关闭的变量。问题是，你不能通过名称字符串访问这些变量（除非你使用某种 eval ）。

If you define getSet in the scope of chart, it will have access to the closed over variables too. The problem is, you can't access those variables by name string (unless you use some kind of eval).

您可以通过将所有私有变量包含在对象中来避免：

You could avoid that by wrapping all your private variables in an object :

function chart() {
    var props = {
        width: 720, // default width
        height: 80 // default height
    }

    function my() {
        // generate chart here, using `width` and `height`
    }

    my.height = function(value) {
        // Call getSet with current my instance as this,
        // 'height' as the first argument, then value
        return getSet.apply(this, arguments.slice().unshift('height'));
    };

    // Works just like your current accessors, on the props object
    function getSet(property, value) {
        if (arguments.length > 1) return props[property];
        props[property] = value;
        return this;
    }

    return my;
}

问题是这不比为每个属性编写几个类似的访问器。你当前的访问器使私人变量虚拟公开，所以为什么不放弃他们并使用公共变量？

The problem is this is not much shorter than writing several similar accessors for each property. Your current accessors make the private variables virtually public, so why not just ditch them and use public variables instead?

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