Mailing Lists: Apple Mailing Lists
Image of Mac OS face in stamp
 
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

A more general signal/slot implementation - 2/2

1- add a method to QObject that would return the address of slot methods from their names. Either a virtual method with predefined name->pointer mappings or a non virtual method that would look into a slot dictionary initialized at construction time. For instance:
<x-tad-bigger> void *KSVG::SVGDocumentImpl::slotFunctionPtr(const char *slotName) const {
if (KWQNamesMatch(slotName, SLOT(slotPaint())))
return (void*)&SVGDocumentImpl::slotPaint;
if (KWQNamesMatch(slotName, SLOT(executeScripts())))
return (void*)&SVGDocumentImpl::executeScripts;
if (KWQNamesMatch(slotName, SLOT(slotSVGContent(QIODevice *))))
return (void*)&SVGDocumentImpl::slotSVGContent;
if (KWQNamesMatch(slotName, SLOT(slotFinishedParsing(bool, const QString &))))
return (void*)&SVGDocumentImpl::slotFinishedParsing;

if (KWQNamesMatch(slotName, SIGNAL(gotDescription(const QString &))))
return (void*)&SVGDocumentImpl::gotDescription;
if (KWQNamesMatch(slotName, SIGNAL(gotTitle(const QString &))))
return (void*)&SVGDocumentImpl::gotTitle;
if (KWQNamesMatch(slotName, SIGNAL(gotURL(const QString &))))
return (void*)&SVGDocumentImpl::gotURL;
if (KWQNamesMatch(slotName, SIGNAL(finishedRendering())))
return (void*)&SVGDocumentImpl::finishedRendering;
if (KWQNamesMatch(slotName, SIGNAL(slotFinishedParsing(bool, const QString &))))
return (void*)&SVGDocumentImpl::slotFinishedParsing;

return QObject::slotFunctionPtr(slotName);
}
</x-tad-bigger>
2- replace the <x-tad-bigger>int</x-tad-bigger><x-tad-bigger> m_function</x-tad-bigger> member attribute in KWQSlot which is the index of the slot function refering to <x-tad-bigger>enum</x-tad-bigger><x-tad-bigger> FunctionNumber</x-tad-bigger> by a <x-tad-bigger>void</x-tad-bigger><x-tad-bigger> *m_functionPtr</x-tad-bigger> or <x-tad-bigger>void</x-tad-bigger><x-tad-bigger> (QObject::*m_functionPtr)()</x-tad-bigger> that would be the address of the slot method. Make KWQSignal a friend of KWQSlot so it can access both attributes.

This implies modifying the KWQSlot constructor, and QObject::connect:
<x-tad-bigger> signal->connect(KWQSlot(</x-tad-bigger><x-tad-bigger>const_cast</x-tad-bigger><x-tad-bigger><QObject *>(receiver), receiver->slotFunctionPtr(member)));
</x-tad-bigger>instead of:
<x-tad-bigger> signal->connect(KWQSlot(</x-tad-bigger><x-tad-bigger>const_cast</x-tad-bigger><x-tad-bigger><QObject *>(receiver), member));
</x-tad-bigger>All the <x-tad-bigger>call</x-tad-bigger> methods in KWQSlot are no longer needed.

3- add a unique signal dispatching method to KWQSignal called from the signaling methods. This method gets the target object and member slot function from each registered KWQSlot and call that function with replicated arguments. A possible implementation uses gcc builtin functions <x-tad-bigger>__builtin_apply_args</x-tad-bigger> and <x-tad-bigger>__builtin_apply</x-tad-bigger> that allows a caller function to call another function with the arguments it received.
<x-tad-bigger>
void</x-tad-bigger><x-tad-bigger> KWQSignal::dispatchSignal() </x-tad-bigger><x-tad-bigger>const</x-tad-bigger><x-tad-bigger>
{

</x-tad-bigger><x-tad-bigger>if</x-tad-bigger><x-tad-bigger> (!_object->_signalsBlocked) {
KWQObjectSenderScope senderScope(_object);
QValueList<KWQSlot> copiedSlots(_slots);
QValueListConstIterator<KWQSlot> end = copiedSlots.end();

</x-tad-bigger><x-tad-bigger>for</x-tad-bigger><x-tad-bigger> (QValueListConstIterator<KWQSlot> it = copiedSlots.begin(); it != end; ++it) {
KWQSlot *slot = &(*it);

</x-tad-bigger><x-tad-bigger>if</x-tad-bigger><x-tad-bigger> (slot->m_functionPtr && slot->m_object) {
</x-tad-bigger><x-tad-bigger>// Copy the arguments to the stack</x-tad-bigger><x-tad-bigger>
</x-tad-bigger><x-tad-bigger>int</x-tad-bigger><x-tad-bigger> *arguments = __builtin_apply_args();
</x-tad-bigger><x-tad-bigger>// Change the first argument (this) to the target object</x-tad-bigger><x-tad-bigger>
arguments[</x-tad-bigger><x-tad-bigger>1</x-tad-bigger><x-tad-bigger>] = slot->m_object.pointer();
</x-tad-bigger><x-tad-bigger>// Apply the slot method to the target object with the initial arguments</x-tad-bigger><x-tad-bigger>
__builtin_apply(slot->m_functionPtr, arguments, </x-tad-bigger><x-tad-bigger>32</x-tad-bigger><x-tad-bigger>);
}
}
}
}
</x-tad-bigger>
I'm not sure what value should have the third arg of <x-tad-bigger>__builtin_apply</x-tad-bigger>, <x-tad-bigger>32</x-tad-bigger> is random.

4- make the signaling functions call the unique signal dispatch method:

<x-tad-bigger> void KSVG::SVGDocumentImpl::finishedParsing(bool error, const QString &errorDesc)
{
void (*call) (KWQSignal *, bool, const QString &) =
(void (*)(KWQSignal *, bool, const QString &))&KWQSignal::dispatchSignal;
call(&_finishedParsing, error, errorDesc);
}
</x-tad-bigger>
Please feel free to comment,

Nicolas Normand
 _______________________________________________
Do not post admin requests to the list. They will be ignored.
Webcore-dev mailing list      (email@hidden)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/webcore-dev/email@hidden

This email sent to email@hidden


Visit the Apple Store online or at retail locations.
1-800-MY-APPLE

Contact Apple | Terms of Use | Privacy Policy

Copyright © 2007 Apple Inc. All rights reserved.