You could try to add the onError event handler to the Tag object. More info can be found here: http://api.jquery.com/error/
If that isn’t enough, you can also look to place try/catch statements where appropriate (haven’t really looked into that yet, so I don’t have a recommendation where to put those)

Tom

I was wondering how you could implement a debug pattern that allows me to catch any errors from plugins within Tag obj.

Best
Nizzy

For this reason, I have created a new function in the core plugin: “hitch”. The name and a good deal of the logic came from the dojo.hitch function.

I won’t go into details right here. I’m going to start writing my new article in a couple of minutes. There I’ll explain everything in detail. I’m happy with the solution I came up with, and I hope you’ll like it too.

In my logic, the “this” context should be :

- the plugin that subscribed to the notification if set
- nothing if it’s a global namespace subscription

This will surely ask some work, some proxy function in the “core” class to be able to tell:

this.subscribeToEvent(plugin,event, function);

and inside :

this.subscribeToEvent = function (plugin,event,function) {
me.getPubsubProvider().subscribe(plugin,event,function,this);
};

and of course :

subscribe:function(plugin, evt, fn,context){
var path = this._constructPath([plugin, evt]);
if (typeof this.subscriptions[path] === ‘undefined’) {
this.subscriptions[path] = [];
}

var subscription_id = this.subscriptions[path].length;
this.subscriptions[path].push({
path:path,
index: subscription_id,
context: context,
callback: fn
});

return (subscription_id);
}

and finally:

notify:function(plugin, evt) {
var path = this._constructPath([plugin, evt]);
if (typeof this.subscriptions[path] !== ‘undefined’) {
for(var i=0,l=this.subscriptions[path].length;i<l;i++){
// make sure we only execute functions, not strings, integers, null's, …
if (typeof this.subscriptions[path][i].callback === 'function') {
if ( this.subscriptions[path][i].context ) {
this.subscriptions[path][i].callback.call(context);
} else {
this.subscriptions[path][i].callback();
}
}
}
}
},

However I'm not good enough in javascript to be sure this is the cool & good way to do it.

This post was mentioned on Twitter by jQuery_Tips: Building your own Javascript library (part 1) #jQuery #Javascript http://j.mp/4WBQ0I...

If you look at the commit history of the pubsub plugin, you’ll see that at one point, I actually did what you suggested:

this.subscriptions[path][i].call(this);

But there were two things with that:
1. This refered to the pubsub scope, which isn’t good
2. This way, callbacks that reside in the global namespace, would have their scope changed to the one of the plugin that notified the event.

At the moment, I’m still thinking about how to solve this. Besides that, I also want to be able to return parameters to the subscribed functions. I’ll find a solution later today (I hope), and you’ll read about it in the next article.

Thanks for your feedback!

really really really good article, thanks & keep up the good work !

I looked at your pubsub plugin ( http://www.codaset.com/theanalogguy/the-analog-guy-javascript-library/source/master/blob/tag/tag.pubsub.js ) and want to ask you :

to notify you run the subscribed anonymous function like so :

this.subscriptions[path][i]();

However this does not tell the function to run in the plugin namespace: in other words “this” does not point to the plugin object that is notified. Just upgrading to :

this.subscriptions[path][i].call( //some code to find the plugin inside window.Tag// );

will automagically set “this” to the notified plugin. Note that Jquery does it :

$(‘#foo’).click(function() {
//this is the jquery object $(‘#foo’)
});

Mickael