Question

I have a function that loads a user object from a web service asynchronously.

I wrap this function call in another function and make it synchronous.

For example:

    private function getUser():User{             var newUser:User;             var f:UserFactory = new UserFactory();              f.GetCurrent(function(u:User):void{                 newUser = u;             });              return newUser;         } 

UserFactory.GetCurrent looks like this:

public function GetCurrent(callback:Function):void{ } 

But my understanding is there is no guarantee that when this function gets called, newUser will actually be the new user??

How do you accomplish this type of return function in Flex?

Answer 1

This way madness lies.

Seriously, you’re better off not trying to force an asynchronous call into some kind of synchronous architecture. Learn how the event handling system works in your favour and add a handler for the result event. In fact, here’s the advice straight from the flexcoders FAQ :

Q: How do I make synchronous data calls?  A: You CANNOT do synchronous calls. You MUST use the result event. No, you can't use a loop, or setInterval or even callLater.  This paradigm is quite aggravating at first. Take a deep breath, surrender to the inevitable, resistance is futile.  There is a generic way to handle the asynchronous nature of data service calls called ACT (Asynchronous Call Token). Search for this in Developing Flex Apps doc for a full description.