Refactoring (《重构》)这本书中有一个例子，挺有代表性，记录如下：
场景
设想有一个戏剧演出团，演员们经常要去各种场合表演戏剧。 通常客户（customer）会指定几出剧目，而剧团则根据观众（audience）人数及剧目类型来向客户收费。 该团目前出演两种戏剧：悲剧（tragedy）和喜剧（comedy）。 给客户发出账单时，剧团还会根据到场观众的数量给出“观众量积分”（volume credit）优惠， 下次客户再请剧团表演时可以使用积分获得折扣。
摘录来自–> 重构: 改善既有代码的设计
代码表示
剧团的演出剧目、种类等信息放在下面的json文件：
// play.json
{
"hamlet": { "name": "Hamlet", "type": "tragedy" },
"as-like": { "name": "As You Like It", "type": "comedy" },
"othello": { "name": "Othello", "type": "tragedy" }
}
账单信息也存储在一个 JSON 文件里,
//invoices.json
[
{
"customer": "BigCo",
"performances": [
{
"playID": "hamlet",
"audience": 55
},
{
"playID": "as-like",
"audience": 35
},
{
"playID": "othello",
"audience": 40
}
]
}
]
打印账单的函数
function statement (invoice, plays) {
let totalAmount = 0;
let volumeCredits = 0;
let result = `Statement for ${invoice.customer}\n`;
const format = new Intl.NumberFormat("en-US",
{ style: "currency", currency: "USD",
minimumFractionDigits: 2 }).format;
for (let perf of invoice.performances) {
const play = plays[perf.playID];
let thisAmount = 0;
switch (play.type) {
case "tragedy":
thisAmount = 40000;
if (perf.audience > 30) {
thisAmount += 1000 * (perf.audience - 30);
}
break;
case "comedy":
thisAmount = 30000;
if (perf.audience > 20) {
thisAmount += 10000 + 500 * (perf.audience - 20);
}
thisAmount += 300 * perf.audience;
break;
default:
throw new Error(`unknown type: ${play.type}`);
}
// add volume credits
volumeCredits += Math.max(perf.audience - 30, 0);
// add extra credit for every ten comedy attendees
if ("comedy" === play.type) volumeCredits += Math.floor(perf.audience / 5);
// print line for this order
result += ` ${play.name}: ${format(thisAmount/100)} (${perf.audience} seats)\n`;
totalAmount += thisAmount;
}
result += `Amount owed is ${format(totalAmount/100)}\n`;
result += `You earned ${volumeCredits} credits\n`;
return result;
}
用上面的数据文件（invoices.json 和 plays.json）作为测试输入，运行这段代码，会得到如下输出：
Statement for BigCo
Hamlet: $650.00 (55 seats)
As You Like It: $580.00 (35 seats)
Othello: $500.00 (40 seats)
Amount owed is $1,730.00
You earned 47 credits
文档信息
- 本文作者：Chaojie Men
- 本文链接：https://menchaojie.github.io/2024/10/20/refactoring/
- 版权声明：自由转载-非商用-非衍生-保持署名（创意共享3.0许可证）