如何在Lodash中创建(可选)可链接函数? [英] How to create (optionally) chainable functions like in Lodash?

问题描述

在Lodash中发现的一种常见且易读的模式是链接".通过链接，上一个函数调用的结果将作为下一个的第一个参数传入.

A common, and very readable, pattern found in Lodash is "chaining". With chaining, the result of the previous function call is passed in as the first argument of the next.

例如Lodash文档中的示例:

Such as this example from Lodash docs:

var users = [
  { 'user': 'barney', 'age': 36 },
  { 'user': 'fred',   'age': 40 }
];

// A sequence with chaining.
_(users)
  .head()
  .pick('user')
  .value();

head和pick都可以在链外使用.

head and pick can both be used outside of a chain as well.

从源头开始，在链中实际调用的方法显然没有什么特别的-因此必须将其链接到初始的_调用和/或value调用.

Going through the source, there is nothing obviously special about the actual methods being called in the chain - so it must be linked to either the initial _ call and/or value call.

标题: https://github.com/lodash/lodash/blob/4.11.0/lodash.js#L6443 选择: https://github.com/lodash/lodash/blob /4.11.0/lodash.js#L12598

一个人如何用自己的方法实现这种模式?并有一个术语吗?

How does one achieve this pattern with their own methods? And does it have a term?

一个例子可能是:

const house = 
    this
        .addFoundation("concrete")
        .addWalls(4)
        .addRoof(true)
        .build();

// Functions being (each can be called by manually as well)

addFoundation(house, materialType) { ... }
addWalls(house, wallCount) { ... }
addRoof(house, includeChimney) { ... }

// And..
build() // The unwrapped method to commit the above

推荐答案

一个如何做的例子

function foo(arr) {
  if (!(this instanceof foo)) {
    return new foo(arr);
  }

  this.arr = arr;
  return this;
}


foo.prototype.add = function(p) {
  this.arr.push(p);
  return this;
}

foo.prototype.print = function() {
  console.log(this.arr);
  return this;
}

foo([1, 2]).add(3).print();

说您也想这样做

foo.add(3).print();

您需要在foo上创建一个方法(不是原型)

You need to create a method on foo (not the prototype)

foo.add = function(p) {
  return foo([p]);
}

foo.add(3).print() // [3]

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