在Node.js中创建模块的副本而不是实例 [英] Create a copy of a module instead of an instance in Node.js

问题描述

这是我有关stackoverflow的第一个问题，希望一切顺利. 我一直在开发游戏(使用corona SDK)，并且我使用Node.js编写了一个小型服务器来处理客户端之间的一些聊天消息，在那里没有问题. 现在，我正在努力扩展这台小型服务器，以执行更多操作，而我想做的是创建一个外部文件(模块)，该文件将容纳一个对象，该对象具有表示我在其中的Room所需的所有功能和变量.我的游戏大厅"中，两个人可以进场比赛，每当我有2个球员准备比赛时，我会为他们创建一个空房间的副本，然后在该房间中初始化游戏. 所以我在主项目文件中有一个数组，其中每个单元都是一个房间，我的计划是将模块导入到该数组中，然后我可以在该特定房间"中初始化游戏，玩家可以玩，游戏将会继续，一切都会很好...但是...我在main.js中的代码:

this would be my first question ever on stackoverflow, hope this goes well. I've been working on a game (using corona SDK) and I used Node.js to write a small little server to handle some chat messages between my clients, no problems there. Now I'm working on expanding this little server to do some more, and what I was thinking to do is create an external file (module) that will hold an object that has all the functions and variables I would need to represent a Room in my games "Lobby", where 2 people can go into to play one against the other, and each time I have 2 players ready to play, I would create a copy of this empty room for them, and then initialize the game in that room. So I have an array in my main project file, where each cell is a room, and my plan was to import my module into that array, and then I can init the game in that specific "room", the players would play, the game will go on, and all would be well... but... my code in main.js:

var new_game_obj = require('./room.js');

games[room_id] = new_game_obj();

games[room_id].users = [user1_name,user2_name];

现在，在我的room.js中，我有一些东西:

Now, in my room.js, I have something of the sort:

var game_logistics = {};

game_logistics.users = new Array();

game_logistics.return_users_count = function(){
    return game_logistics.users.length;
}

module.exports = function() {
    return game_logistics;
}

到目前为止，一切都很顺利，我可以简单地进行以下操作:

So far so good, and this work just fine, I can simply go:

games[room_id].return_users_count()

然后我将得到0或1或2，具体取决于加入该会议室的用户数量. 一旦我打开一个新房间，问题就会开始，因为Node.js会实例化我创建的模块，而不是对其进行复制，即使现在我创建一个新房间，即使我删除和/或删除了旧房间，也是如此，它会包含我已经更新的旧房间中的所有信息，而不是新的洁净室中的所有信息.示例:

And I will get 0, or 1, or 2, depending of course how many users have joined this room. The problems starts once I open a new room, since Node.js will instance the module I've created and not make a copy of it, if I now create a new room, even if I eliminated and/or deleted the old room, it will have all information from the old room which I've already updated, and not a new clean room. Example:

var new_game_obj = require('./room.js');

games["room_1"] = new_game_obj();
games["room_2"] = new_game_obj();

games["room_1"].users = ["yuval","lahav"];

_log(games["room_1"].return_user_count()); //outputs 2...
_log(games["room_2"].return_user_count()); //outputs 2...

即使这样做:

var new_game_obj = require('./room.js');
games["room_1"] = new_game_obj();

var new_game_obj2 = require('./room.js');
games["room_2"] = new_game_obj2();

games["room_1"].users = ["yuval","lahav"];

_log(games["room_1"].return_user_count()); //outputs 2...
_log(games["room_2"].return_user_count()); //outputs 2...

给出相同的结果，它是我制作的所有副本"中同一模块的所有相同实例. 所以我的问题就这么简单，我如何创建原始模块的干净"副本，而不是一遍又一遍地实例化它，实际上最后只有一个凌乱的房间?

Gives the same result, it is all the same instance of the same module in all the "copies" I make of it. So my question as simple as that, how do I create a "clean" copy of my original module instead of just instancing it over and over again and actually have just one messy room in the end?

推荐答案

您正在做什么(用返回的内容替换require()调用)；

What you're doing is this (replacing your require() call with what gets returned);

var new_game_obj = function() {
    return game_logistics;
}

因此，每次调用new_game_obj时，都会返回game_logistics的 same 实例.

So, every time you call new_game_obj, you return the same instance of game_logistics.

相反，您需要使new_game_obj返回game_logistics的 new 实例；

Instead, you need to make new_game_obj return a new instance of game_logistics;

// room.js
function Game_Logistics() {
    this.users = [];

    this.return_users_count = function(){
        return this.users.length;
    };
}

module.exports = function() {
    return new Game_Logistics(); 
}

这是一种观念上的转变.您会看到我们在module.exports中的Game_Logistics上使用new在每次调用Game_Logistics的 new 实例时.

This is quite a shift in mentality. You'll see that we're using new on Game_Logistics in module.exports to return a new instance of Game_Logistics each time it's called.

您还将看到，在Game_Logistics中，this到处都在使用，而不是Game_Logistics；这是为了确保我们引用的是正确的的 instance 而不是构造函数.

You'll also see that inside Game_Logistics, this is being used everywhere rather than Game_Logistics; this is to make sure we're referencing the correct instance of Game_Logistics rather than the constructor function.

我还大写了您的game_logistics函数，以遵循广泛使用的命名约定，即构造函数应大写(更多信息).

I've also capitalized your game_logistics function to adhere to the widely-followed naming convention that constructor functions should be capitalized (more info).

当您使用多个函数实例时，建议利用JavaScript中的原型链.您可以阅读有关"JavaScript原型继承*"的各种文章(例如这 )，但目前，以上已可以满足您的需求.

Taking advantage of the prototype chain in JavaScript is recommended when you're working with multiple instances of functions. You can peruse various articles on "javascript prototypical inheritance* (e.g. this one), but for now, the above will accomplish what you need.

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