Hi,
Den 30. mai 2012 15:23, skrev ext Diego Iastrubni:
> On Wed, May 30, 2012 at 4:11 PM, Olivier Goffart <oliv...@woboq.com
> <mailto:oliv...@woboq.com>> wrote:
>
> On Saturday 26 May 2012 12:51:23 Stephen Kelly wrote:
> > Hi,
> >
> > There is a discussion on a kde list touching on whether there is a
> > replacement for QtScript in Qt 5.
> >
> >
> http://thread.gmane.org/gmane.comp.kde.devel.kwrite/32993/focus=75079
> >
> > Is the QJSEngine the start of public API providing a replacement for
> > QtScript?
>
>
> So as an application developer, which wants to add JS scripting
> capabilities to JavaScript code (so user can extend my application).
> What are my options?
>
> How can I load JS files, and call some specific functions defined
> internally in those JS? I will also need to expose some API of mine to
> those JS files.
>
> (Note: I am not talking about QML at all)
>
The QJSEngine/Value API already supports that use case. The code would
be 99% the same as with QtScript, if you're familiar with that.
QJSEngine engine;
engine.evaluate("function add(a, b) { return a+ b; }"); // contents of
some file
QJSValue addFun = engine.globalObject().property("add"); // get the
function from the script
qDebug() << addFun.call(QJSValueList() << 1 << 2).toNumber();
Exposing a QObject is also similar to QtScript:
MyQObject *obj = ...;
engine.globalObject().setProperty("myQObject", engine.newQObject(obj));
engine.evaluate("myQObject.someSlot()");
What's missing is the more low-level API, like QScriptContext that
Olivier mentioned. There's currently no API for exposing a "plain C
callback" with QJS; everything has to go through the QObject binding.
You can provide individual functions to JS by only exposing a particular
QObject wrapper function, e.g.:
engine.globalObject().setProperty("myGlobalFunction",
engine.newQObject(obj).property("someSlot"));
There's currently no API for dealing with exceptions. QtScript had
uncaughtExceptionBacktrace() and friends; in QJS there is only
QJSValue::isError() as of yet. You can get error messages, stack trace
etc. by querying properties of error objects.
QJS has no debugging API or tools. V8 provides a public debugging API,
but we'd have to be very careful if QJS were to wrap that (again, to
avoid leaking back-end details).
Also worth mentioning is the quirky
QScriptEngine::setProcessEventsInterval(), which was annoying to support
with both JSC and V8 (and didn't ever work reliably even with the
original back-end, because the engine could potentially call into a
long-running C++ function, which invalidated the promise of respecting
the user-specified interval). If you need to execute potentially
long-running JavaScript, you'll need to do it from a separate thread
with QJS.
Best regards,
Kent
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