I ran into a problem a few days ago. I built this really nifty queue module. It removes elements once they're old as defined by the key "endTime" (which come to think about it, maybe that could be a future enhancement to specify how to "expire", but I digress). Here is the problem, I needed a second queue. Well I can't just require my queue module in because it's cached and well it's not a "new" instance.
So for example.
var queue = require('queue.js');
var queue2 = require('queue.js');
queue.add({endTime : 1234});
queue2.add({enddTime : 2345});
// Assume queue.element returns the head of the queue
console.log(queue.element());
Output
>> {endTime : 2345}
// Assume queue.entire returns the entire queue
console.log(queue2.entire());
Output
>> {endTime : 1234}, {endTime : 2345}
As you can see you don't get a unique queue.
I found some examples around the interwebs and gave it a try. I have a problem with the common approach shown below.
var queue = function(){
var self = this;
self.local_queue = [];
var funcs = {
add : function (obj){
...... stuff ......
},
entire : function(){
..... stuff..........
}
...
}
}
module.exports = function(){
return new queue();
}
I don't like implementing my functions IN the surrounding function (the add: function example).
I prefer the following:
var add = function(obj){
... stuff ...
}
...
...
var queue = function(){
var self = this;
self.local_queue = [];
var funcs = {
add : add,
entire : entire,
...
}
}
module.exports = function(){
return new queue();
}
The problem is that my functions were not able to reference self.
So I finally worked around this like this.
var add = function(self, obj){
... stuff ...
}
...
...
var queue = function(){
var self = this;
self.local_queue = [];
var funcs = {
add : function(obj){return add(self, obj)},
...
}
}
module.exports = function(){
return new queue();
}
If you notice now we have a self reference being passed to the function, all is now well in queue land.
Now when I require in it looks something like this.
var queue = require('./queue')
var queue1 = new queue();
var queue2 = new queue();
Now any adds and removes all affect only their own queues.
If you have a better cleaner way to implement this I'd be happy to see it.