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

[Rami Ojares / AMG Oy]

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
>>
>