Signal/Slot clarification [SOLVED]
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Hi there,
Any type of parameter within the C++ library is possible. Even user defined structures etc. It is just a special way to call (member) functions automatically when a event occurs. So any class can create a signal an can be paired to a slot.
Might be a good suggestion to read the signal/slot information before venturing into this part of coding. Isn't all that difficult to understand.
"http://doc.qt.nokia.com/4.7-snapshot/signalsandslots.html"
Greetz -
thank you for the answer. I have the following code:
@void mySlot(const std::list<MyClass*> &);
void
MyManager::mySlot(const std::list<MyClass*> &theList)
{
std::cout << "mySlot " << std::endl;
}void mySignal(const std::list<MyClass*> &theList);
TestThread ::TestThread (std::list<MyClass*>&theList, QObject *parent)
: QThread(parent), myList(theList)
{}
void
TestThread ::run()
{
...
emit mySignal(myList);
}@@QObject::connect(threadObj, SIGNAL(mySignal(std::list<MyClass*>)), this, SLOT(mySlot(std::list<MyClass*>)));@
the slot is never fired. What's wrong?
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[quote author="blackbelt" date="1343654430"]Is the signal/slot pair working like a callback mechanism? If I want to create a custom pair signal/slot can I pass as parameter every kind of object? Is this wrong?
thanks in advance[/quote]
It's more like publisher/subscriber pattern. You can have any number of slots being connected to one signal.
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QObject::connect prints a qDebug message when signal-slot-connection fails. Do you see such a message in debug mode?
If not: Is the connection made before emitting the signal?And finally: Try not to mix Qt and STL when not absolutely necessary. For example, use QList or QLinkedList instead of std::list.
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Signal-slot connections between threads have some more restrictions than the normal, direct ones. That is because the mechanism needs to be able to serialize and deserialize the data. I note from your code that you seem to be using multiple threads.
Did you register your type to the [[doc:QMetaType]] system?
