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JavaScriptでDCI的なものを実装してみた例
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| // 銀行口座 | |
| var BankAccount = function (balance) { this.balance = balance; }; | |
| BankAccount.prototype.increase = function (money) { this.balance += money; }; | |
| BankAccount.prototype.decrease = function (money) { this.balance -= money; }; | |
| // ロール: 送信側 | |
| var Sender = function () {}; | |
| Sender.prototype.send = function (money, to) { | |
| this.decrease(money); | |
| to.onReceived(money, this); | |
| }; | |
| // ロール：受信側 | |
| var Receiver = function () {}; | |
| Receiver.prototype.onReceived = function (money, to) { | |
| this.increase(money); | |
| }; | |
| // コンテキスト: 口座間送金 | |
| var TransferContext = function (from, to) { | |
| Object.keys(TransferContext.prototype).filter(function (key) { | |
| return 'function' == typeof this[key]; | |
| }.bind(this)).forEach(function (key) { | |
| var func = this[key]; | |
| this[key] = function () { | |
| var mixin = function (obj, ctx) { | |
| var proto = obj.__proto__; | |
| obj.__proto__ = ctx; | |
| obj.__proto__.__proto__ = proto; | |
| } | |
| var cleanup = function (obj) { | |
| obj.__proto__ = obj.__proto__.__proto__; | |
| } | |
| mixin(from, Sender.prototype); | |
| mixin(to, Receiver.prototype); | |
| func.apply(this, arguments); | |
| cleanup(from); | |
| cleanup(to); | |
| }; | |
| }.bind(this)); | |
| this.from = from; | |
| this.to = to; | |
| }; | |
| TransferContext.prototype.transfer = function (money) { | |
| this.from.send(money, this.to); | |
| }; | |
| var from = new BankAccount(10); | |
| var to = new BankAccount(10); | |
| (new TransferContext(from, to)).transfer(10); | |
| console.log(from.balance, to.balance); // 0 20 | |
| console.log(from.send, to.onReceived); // undefined undefined |
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