[Qt-qml] Merging V8 into qtdeclarative.git#master

[aaron.kennedy at nokia.com]

Hi Girish,

On 05/07/2011, at 7:39 PM, "ext Girish Ramakrishnan" <girish at forwardbias.in> wrote:

> Hi Aaron,
> This is great news!
> 
> I am wondering what the move to V8 means in terms of portability of Qt
> to platforms other than the ones listed in
> http://code.google.com/apis/v8/build.html. What about MIPS, SH4,
> pre-leopard Mac etc?  Is the doc page is out of date or will QML not
> support these platforms?

Unfortunately you are correct - QML's platform portability will be limited to the platforms supported by V8.  As you note, this initially will exclude ports to older Mac OS X, MIPS and SH4.  On a positive note the MIPS port of V8 seems very nearly complete (if not already complete), so we could expect to support that pretty easily.  Porting V8 to a new processor architecture is quite involved, so I wouldn't expect SH4 support unless someone is very committed.

Cheers,

Aaron

> On Tue, Jul 5, 2011 at 9:50 AM,  <aaron.kennedy at nokia.com> wrote:
>> Hi,
>> 
>> Tomorrow we will merge the qtdeclarative.git#v8 branch into qtdeclarative.git#master.  This change switches the JavaScript engine QML uses from JavaScript Core to V8 (http://code.google.com/p/v8/).
>> 
>> In the past QML accessed the JavaScript engine indirectly through QtScript, but with V8 we integrated it directly against V8's native C++ API.  Consequently, in addition to the raw JavaScript performance improvements we get for "free", QML can leverage some of V8's unique features to give a better JavaScript experience.
>> 
>> In a perfect world, other than their apps running slightly faster, QML users should notice no change.  However, there are a couple of known regressions to be aware of:
>> 
>>    1. Creator integration will probably not work as smoothly in the short term - at the very least the JavaScript debugging will not work.
>>    2. Any QML API that relies on QML's undocumented ability to set and get QScriptValue properties will no longer work.
>>    3. Any application that provides a QScriptValue based QML module API will no longer work.  As module APIs are an unreleased feature anyway, hopefully this wont be a big problem.
>> 
>> If you encounter any other breakage, it is probably a bug - so please report it!
>> 
>> One goal in qt5 is to allow applications to expose their own JavaScript based APIs to QML.  Right now, it is not clear whether this will be accomplished by porting all of QtScript to V8, or by exposing a new, smaller JavaScript API that just wraps V8.  If anyone has any strong opinions on the matter, now would probably be a good opportunity to express them :)
>> 
>> Cheers,
>> 
>> Aaron
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