Question

I want to do something like this:

function x(){
    var o = {};
    o.__defineGetter__('y', function(){
        return new Date();
    });

    return o.y;
}

var z = x();
console.log(z);
//Wait 1 second
console.log(z); //Date should be one second past the last printing

Of course, this doesn’t work because o.y is evaluated when it is returned. I’m looking for a way to return a variable that acts as a getter. The following example gives me hope that something like this could be possible:

function x(context){
    //Bind the getter to the passed in scope
    context.__defineGetter__('y', function(){
        return new Date();
    });
}

x(this);
console.log(y);
//Wait 1 second
console.log(y); //Date is one second past last printing

Has anyone ever tried to do something like this?

Yes, I’m familiar with other ways to model similar behavior using different syntax. I just want this particular syntax to work for a special scenario.

Thanks,

Chris

Answer 1

function x(){
    var o = function() {};
    o.__proto__ = {
           valueOf:  function() { 
               return new Date().toString(); 
           }
     };

    return o;
}

var z = x(); 
console.log(z);  // Tue Mar 13 2012 14:10:10 GMT+0200 (GTB Standard Time)
setTimeout(function() { 
   console.log(z); // Tue Mar 13 2012 14:10:12 GMT+0200 (GTB Standard Time)
}, 2000);