[Laszlo-dev] Continued: swf9 and attribute constraint peculiarity

[P T Withington]

This is related to:

http://jira.openlaszlo.org/jira/browse/LPP-7958

So, it appears will still need to improve the error reporting when you  
attempt to write a constraint on an object that does not participate  
in the OL event system.

http://jira.openlaszlo.org/jira/browse/LPP-7344

But, maybe with the improved runtime error reporting (just added to  
trunk), these errors will be more obvious, instead of silently failing?

On 2009-10-05, at 09:50, Rami Ojares / AMG Oy wrote:

> For completeness sake here is the correct formulation of the idea I  
> was trying to achieve (I quess I should have posted this on the user  
> side)
>
> <canvas debug="true">
>   <view name="test">
>             <attribute name="someArr" value="new Array()"/>
>             <view width="100" height="100" bgcolor="$ 
> {this.hasElements(parent.someArr) ? 'red' : 'blue'}" x="30" y="45">
>           <method name="hasElements" args="attr">
>               return attr.length != 0;
>           </method>
>           <handler name="onclick">
>               parent.someArr.push("foo")
>               parent.setAttribute("someArr", parent.someArr);
>           </handler>
>       </view>
>         </view>
> </canvas>
>
> Lesson learned:
> Use methods for more complex calculations in constraints and name  
> the attributes (dependencies) as arguments.
>
> - rami
>
> Max Carlson wrote:
>> That's correct.  Constraints will only work properly with OL  
>> attributes.  Things like array.length don't tell the runtime when  
>> they change, so the constraint doesn't know when to update...
>>
>> Rami Ojares / AMG Oy wrote:
>>> It probably has something to do with the dependencies...
>>> Maybe my code is incorrect when it refers to  
>>> "parent.someArr.length" in the constraint?
>>> Am I allowed only to refer to attribute names of laszlo nodes in  
>>> constraints?
>>> So that dependencies can be constructed properly.
>>>
>>> - rami
>>>
>>> Rami Ojares / AMG Oy wrote:
>>>> Hi,
>>>>
>>>> I stumbled upon a problem with swf9 (and up) attribute constraints.
>>>>
>>>> Here is sample code that works in swf8 but fails silently in swf9
>>>>
>>>> <!-- The problem is with setting of bgcolor attribute -->
>>>> <canvas debug="true">
>>>>   <view name="test">
>>>>             <attribute name="someArr" value=" new Array()"/>
>>>>             <view width="100" height="100" bgcolor="$ 
>>>> {parent.someArr.length == 0 ? 'red' : 'blue'}" x="30" y="45">
>>>>           <handler name="oninit">
>>>>               Debug.inspect(parent.someArr.length == 0)
>>>>           </handler>
>>>>       </view>
>>>>        </view>
>>>> </canvas>
>>>>
>>>> Here the same thing slightly modified so that it works in swf9
>>>>
>>>> <!-- The problem is with setting of bgcolor attribute -->
>>>> <canvas debug="true">
>>>>   <view name="test">
>>>>             <attribute name="someArr" value=" new Array()"/>
>>>>             <view width="100" height="100" bgcolor="$ 
>>>> {this.hasErrors() ? 'red' : 'blue'}" x="30" y="45">
>>>>           <handler name="oninit">
>>>>               Debug.inspect(parent.someArr.length == 0)
>>>>           </handler>
>>>>           <method name="hasErrors">
>>>>               return parent.someArr.length == 0;
>>>>           </method>
>>>>       </view>
>>>>         </view>
>>>> </canvas>
>>>>
>>>> So it seems to me that something gets screwed parsing attribute  
>>>> constraints in swf9.
>>>> Any ideas?
>>>>
>>>> - rami
>>>
>>
>