Bind with inverse warning

Question

hi,
To learn how the bidirectional binding works I made a couple of small snippets based on a textfield and a button. The objective is that with both editing and clicking on the button the string str changes. The button can be seen as the model that changes the value of the var in the other direction.
(println is just for debug)
This works:
var str = "" on replace{
  println (str)
mainStage.scene.content = [
TextBox {
     text: bind str with inverse
     columns: 12
     selectOnFocus: true
SwingButton {
        translateX:50
     text: "ok"
     action: function() { str = "hello" }
]I made an object containing a string which also works:
class test{
    var str = "" on replace {
        println (str)
def mytest = test{ };
mainStage.scene.content = [
TextBox {
     text: bind mytest.str with inverse
     columns: 12
     selectOnFocus: true
SwingButton {
        translateX:50
     text: "ok"
     action: function() { mytest.str = "hello" }
]Finally I tried to go one level further and made the string come from another object this works but I get a warning:
class test{
    var t : test1 = test1{} ;
class test1{
    var str = "" on replace {
        println (str)
def mytest = test{};
mainStage.scene.content = [
TextBox {
     text: bind mytest.t.str with inverse
     columns: 12
     selectOnFocus: true
SwingButton {
        translateX:50
     text: "ok"
     action: function() { mytest.t.str = "hello" }
warning: Target of variable select expression is not re-evaluated for bind with inverse. You may want to rewrite like the following:
def obj = <expression-without-bind>;
def x = bind obj.variableName with inverse;
        text: bind mytest.t.str with inverseWhen I change the var t into def this doesn't solve the warning. And it's needed to have the str variable as a var because in real apps this will be coming from the model logic that changes this value. So why showing this warning anyway , I used def for mytest object so that the actual object can't be changed ?
Edited by: guyvo on Jan 9, 2010 9:39 PM

Answer 1

hi stuart,
Thanks for reading and give your comments. I red a few of your blogs , interesting stuff and yes maybe you must write one dedicated on the bind with inverse !
In my app the model is mapped from XML fields into a few class objects. I instantiate these classes at startup and then read and parse my XML data into my objects. The objects will remain living until the script exits. As I bind my view with the model classes and visa versa with a double bind inverse, I think I can be pretty sure these wont garbage collected because of the double links.
Make sense that the "def temp" is only a local variable of the HorizontalBar and becomes no part of the class declaration itself. I just use this def to avoid the warning.
I even tried to add a function with a variable when creating the object without a problem although kind a useless :
HorizontalBar {
                    var y;
                    function foo (){ y = 10;};
                    disable:bind dis;
                    def temp = c.light[j];
width: 200
height: 20
posx: 10
posy: 10 + y
valmodel: bind temp.ivalue with inverse
-G