[Laszlo-user] Laszlo function as Array.sort argument

[P T Withington]

It _is_ getting called.  For some reason, your Debug.write is failing  
to send any output:

lzx> Debug.trace(canvas, 'laszloMethod')
lzx> [1,2,3].sort(canvas.laszloMethod)
TRACE: [394491.00] laszloMethod.apply(«undefined», [1, 2])
laszloMethod( 1 , 2 )
TRACE: [394501.00] laszloMethod -> 0
TRACE: [394505.00] laszloMethod.apply(«undefined», [1, 3])
laszloMethod( 1 , 3 )
TRACE: [394512.00] laszloMethod -> 0
TRACE: [394516.00] laszloMethod.apply(«undefined», [1, 2])
laszloMethod( 1 , 2 )
TRACE: [394523.00] laszloMethod -> 0
TRACE: [394527.00] laszloMethod.apply(«undefined», [2, 3])
laszloMethod( 2 , 3 )
TRACE: [394536.00] laszloMethod -> 0
«Array(3)#15| [1, 2, 3]»
lzx>

Oh, hah-hah.  I see why.  Because laslzoMethod is a method, it expects  
a 'this' argument, and our compiler inserts an implicit `with (this)`  
around your method body, but you are calling it as a function, and  
`this` is undefined in that case (see the trace output above).  So  
your code is turning into `with (undefined)` and I bet that causes the  
global reference to Debug to fail.  Amusingly, tracing the method  
makes the debug output work.  I can't really explain that.

If you were to make a closure to call your method, it should work:

lzx> Debug.untrace(canvas, 'laszloMethod')
lzx> [1,2,3].sort(function (a, b) { return canvas.laszloMethod(a, b) })
laszloMethod( 1 , 2 )
laszloMethod( 1 , 3 )
laszloMethod( 1 , 2 )
laszloMethod( 2 , 3 )
«Array(3)#57| [1, 2, 3]»
lzx>

On 2008-01-09, at 14:28 EST, Pablo Kang wrote:

> Btw, I know that I can call a laszloMethod from a Javascript  
> function like:
>
>  <method name="javascriptFunction" args="n1,n2">
>      return canvas.laszloMethod(n1,n2);
>  </method>
>
> What I want to know is why it is I can't pass in the the  
> laszloMethod directly.
>
> Thanks,
> pablo
>
> On Wed, 9 Jan 2008, Pablo Kang wrote:
>
>> Anyone know why passing in a function defined with an LZX method  
>> tag into Array.sort doesn't work? Here's a test case:
>>
>> <canvas debug="true">
>>
>>   <method name="laszloMethod" args="n1,n2">
>>       Debug.write('laszloMethod(', n1, ',', n2, ')');
>>       return 0;
>>   </method>
>>
>>   <script>
>>       function javascriptFunction(n1,n2) {
>>           Debug.write('javascriptFunction(', n1, ',', n2 ,')');
>>           return 0;
>>       }
>>   </script>
>>
>>   <handler name="oninit">
>>       var arr = [ 1,2,3 ];
>>
>>       Debug.write('-- Javascript Function --');
>>       arr.sort( javascriptFunction );
>>
>>       Debug.write('-- Laszlo Method --------');
>>       arr.sort( canvas.laszloMethod );
>>   </handler>
>>
>> </canvas>
>>
>> pablo
>>
>>
>>