how to listen a function?

[villin.zhou]

I have created two functions aa and bb. now I hope, when I call aa, the bb will be also invoked. How to do that? I mean, don't write the bb invoked code in aa. I hope just like "dojo.connect(a,"aa",b,"bb');", I don't know how does the dojo realize it.

[cgishack]

would something like below work?

function connect(function1, function2)
{
	eval(function1)();
	eval(function2)();
}

function aa()
{
	alert('I am aa function');
}


function bb()
{
	alert('I am bb function');
}

//TEST IT ALL
connect('aa','bb');

Drew

[A1ien51]

Another idea to play with:

function foo(fnc){
 fnc();
}

function bar(){
  alert("bar");
}

foo(bar);

Eric

[villin.zhou]

Thanks for your response. I'm sorry. recently, I am learning the dojotoolkit. maybe, I didn't describe the question clearly.
This is the test code I used in my page with dojotoolkit:
<script src="dojo.js"></script>
<script>
function ab(){
this.a = function(){alert("b");}
}
function ac(){
this.a = function(){alert("c");}
}
var b = new ab();
var c = new ac();
dojo.connect(b,"a",c,"a"); // here use c.a to listen b.a
b.a(); //b.a is called, and c.a is also invoked
</script>

As above, I call b.a, but c.a is also invoked, I don't know how does it work?
in the ab.a, I don't write any code to invoke the ac.a, but it do, why?
I mean how does the dojo connect these two functions.
I guess the dojotoolkit modify my b.a function, and add some codes to call the c.a, but I can't find out it.
I have read the source codes of dojo, but didn't find any clue.
Is there anyone familiar with dojotoolkit?
give me some clues, please!
thank you!

[Mr Moo]

While I'm not sure what the dojo implementation looks like, here's a quick one I hacked together (this type of thing is part of something called Aspect Oriented Programming, hence the name of the object).

    Aspect = {
        after: function(a, b, c, d) {
            var ab = a[b];
            a[b] = function() {
                ab.apply(a, arguments);
                c[d].apply(c, arguments);
            }
        }
    }; 

So, when you call Aspect.after(...) it creates a copy of the original function and then replaces it with a function which first calls the copy and then calls the "listening" function, both with the same arguments, and both in the context of their object.

I have put a quick sample here: Aspect.

You can read about the apply function here.

[villin.zhou]

Great! This is just what I need.
Thank you,Mr Moo, and two brothers above, you do me a big favor!