異步並行與可變參數的回調

Question

我是不是與此代碼真的很高興：

async.parallel([ 
    getThing1, 
    getThing2, 
    getThing3 
], function(err, responses) { 
    next.ifError(err); 

    var thing1 = responses[0], 
     thing2 = responses[1], 
     thing3 = responses[2]; 

    // business 
}); 

我寧願它看起來像這樣，點菜要求：

async.parallel([ 
    getThing1, 
    getThing2, 
    getThing3 
], function(err, thing1, thing2, thing3) { 
    next.ifError(err); 

    // business 
}); 

這是我「已經結束了：

async.variadic = function(fn) { 
    return function(err, responses) { 
    return fn.bind(this, err).apply(this, responses); 
    } 
} 

async.parallel([ 
    getThing1, 
    getThing2, 
    getThing3 
], async.variadic(function(err, thing1, thing2, thing3) { 
    next.ifError(err); 

    // business 
})); 

問題：

我是否在fn.bind(this, err).apply(this, responses);中正確使用this？

有沒有一種現有的方法來做到這一點與異步庫？

---

更新：這是一種不同的方式來實現：

async.variadic = (function() { 
    var _async = {}; 
    _async.prototype = async; 
    _async.parallel = function(tasks, callback) { 
    return async.parallel(tasks, function(err, responses) { 
     return callback.bind(this, err).apply(this, responses); 
    }); 
    }; 
    return function() { 
    return _async; 
    }; 
})(); 

async.variadic().parallel([ 
    getThing1, 
    getThing2, 
    getThing3 
], function(err, thing1, thing2, thing3) { 
}); 

I think I like this one most. Is this a good way to accomplish the task? 

---

下面是用不同的想法jsperf：http://jsperf.com/variadic-async

Answer 1

我個人比較喜歡第一種方法。該variadic函數知道少講發生了什麼事，甚至可能被抽象更多：

function variadic(fn) { 
    var self = this; 
    return function(err, responses) { 
    responses.unshift(err); 
    return fn.apply(self, responses); 
    } 
} 

async.variadic = variadic.bind(async); 

async.parallel([ 
    function(cb) { 
     cb(null,'1') 
    }, 
    function(cb) { 
     cb(null,'2') 
    }, 
    function(cb) { 
     cb(null,'3') 
    }, 
], async.variadic(function(err, thing1, thing2, thing3) { 
    console.log(this); 
    console.log(thing1,thing2,thing3); 
    // business 
}));