True. Good point. Event handler attributes are assumed to contain code. Most attributes are of a type like string or number, and will need braces to get a value treated as code. I'm not sure if there are other attributes beside event handlers which are also assumed to contain code, but it wouldn't surprise me if there are some others.
Sid Maskit Partner CraftySpace Better Websites for a Better World http://www.CraftySpace.com blog: http://smaskit.blogspot.com/ ----- Original Message ---- From: Amy <[EMAIL PROTECTED]> To: flexcoders@yahoogroups.com Sent: Thursday, July 31, 2008 1:01:13 PM Subject: [flexcoders] Re: NaN and Infinity showing in output - How to modify? --- In [EMAIL PROTECTED] ups.com, Sid Maskit <[EMAIL PROTECTED] > wrote: > > I think I see your point here, and I guess that I have not made mine clearly enough, so here is a little more on this. > > When we say text="{myNumber} ", we are really setting up whatever is within the braces as an event handler for the event dispatched whenever myNumber changes. If we think of binding as setting up that relationship, then yes, everything in this thread is using binding. However, I think it is common for beginners to think of that statement as binding the text attribute to the latest value of myNumber, and to think of binding as doing no more than such assignments. > > I think it is important part of learning flex to realize that one can do much more than that. In the largest sense, one can do almost anything that is possible with a single ActionScript statement, so long as it returns a valid value for the attribute to which it is assigned, in this case the text attribute. For example, one could do something rather complicated, like this: > > text="{(myNumber != 0) ? myFunction() : myOtherFunction( )}" > > So long as both functions returned a value that could be validly assigned to the text attribute, this approach is valid, and we can obviously do any valid ActionScript within either function. I'm not sure that this approach would be a best practice, but the point is that we are doing a lot more than simply taking the value of myNumber and assigning it to text. > > Finally, although I do not think you meant to imply this, I think it is worth saying that one cannot use ActionScript within an assignment to an MXML attribute without using braces. Well, one can, but it will be treated as a string, not as code to be run. In at least some instances, MXML will run code that is not within braces, for instance <mx:LinkBar id="chartSwitcher" borderStyle= "solid" itemClick="invalida teDisplayList( )" /> It's not treating the text within the itemClick property as a string, but as code to be run. I'm not certain exactly where the line is, but you don't ALWAYS have to enclose your as expressions in brackets to get them to run. -Amy
