[Laszlo-dev] RFC: Proposal for setter API change

[André Bargull]

On 10/2/2008 10:22 PM, André Bargull wrote:
> On 10/2/2008 8:57 PM, P T Withington wrote:
>> On 2008-10-02, at 10:55EDT, André Bargull wrote:
>>
>>>>
>>>> In the default event system, what you get if you don't write a 
>>>> custom  setter, sends an event every time you call setAttribute.  
>>>> It does  _not_ make any optimization to not send events if you 
>>>> happen to set an  attribute to a value it already has.
>>>>
>>> A side note for the interested reader:
>>> It's possible to turn on manually this optimization if you pass as 
>>> the third argument to "setAttribute()" ?true?, e.g.
>>> foo.setAttribute("text", "hello world!", true)
>>> (That way the setter is not called when the value did not change.)
>>
>> My head hurts trying to process that logic.  Too many negatives.
>>
>> This seems like an incredibly dangerous optimization, because if you 
>> have a custom setter, how can the generic code know whether or not 
>> the value 'changed'?  E.g., suppose the custom setter ensures your 
>> value is in a particular range or rounded to a particular granularity?
>>
>> When did setAttribute grow this featureXXXXXXXbug?  I don't recall 
>> seeing an API review for this.
>
> It's there since 4.0.5

I'm searching for a specific changeset, but take a look what I found:
>   r6110 | max | 2007-08-17 05:11:57 -0700 (Fri, 17 Aug 2007) | 24 lines
>
>   Change 20070816-maxcarlson-f by maxcarlson at plastik on 2007-08-16 
> 20:44:10 PDT
>       in /Users/maxcarlson/openlaszlo/wafflecone
>       for http://svn.openlaszlo.org/openlaszlo/branches/wafflecone
>
>   Summary: UPDATED: Add flag to only setAttribute() if it the value 
> passed in changed.
>
>   New Features:
>
>   Bugs Fixed:
>
>   Technical Reviewer: ptw
>   QA Reviewer: promanik
>   Doc Reviewer: (pending)
>
>   Documentation:
>
>   Release Notes:
>
>   Details: Add a flag that only sets the attribute if its value 
> changed.  It's a common pattern to only set an attribute when it 
> changed.  W
> ith inlining of setAttribute it will also make sense for performance.
>
>
>   Tests: IWFM