QTimer::singleShot - forward parameter to SLOT called

McLion

Hi

I'd like to do something like this:

QTimer::singleShot(5000, this, SLOT(MySlot(iID)));

to get the ID (can be 1 to 16) and know which ID did kick off the singleShot.
However, that seems not to be possible with on-board tools.

Any idea how this can be easily implemented?
Thanks
McL

m.sue

Hi,
how about

QTimer::singleShot(5000, this, [] () {MySlot(0); });
QTimer::singleShot(5000, this, [] () {MySlot(1); });

etc. or

for (iId=0; iId < 2; ++iId)
  QTimer::singleShot(5000, this, [iId] () {MySlot(iId); });

if you want to keep the variable.
-Michael.

McLion

@m.sue said in QTimer::singleShot - forward parameter to SLOT called:

[] {MySlot(0); }

Hhmmm ..
Is this documented somewhere: ... [] {MySlot(0); }.. frankly, I have no clue and the compiler doesn't like it either.

m.sue

@McLion: You are right. I forgot the (): [] () {MySlot(0); }
It's the lambda function of C++11.

McLion

@m.sue
Quickly added CONFIG += c++11 ... still no joy.
I get expected primary-expression before '[' token

VRonin

Ancient compiler and/or Qt version I guess. You can use QSignalMapper then:

QSignalMapper* idMapper= new QSignalMapper(this)
connect(idMapper,SIGNAL(mapped(int)),this,SLOT(MySlot(int)));
for (int iId=0; iId < 2; ++iId){
QTimer* tempTimer=new tempTimer(this);
tempTimer->setInterval(5000);
tempTimer->setSingleShot(true);
idMapper->setMapping(tempTimer, iId);
connect(tempTimer,SIGNAL(timeout()),idMapper,SLOT(map()));
connect(tempTimer,SIGNAL(timeout()),tempTimer,SLOT(deleteLater()));
tempTimer->start();
}

McLion

@VRonin
Thanks!
any idea why it builds ok but crashes on this line?
iGUIidMapper->setMapping(tempTimer, iGUIid);

VRonin

@McLion In all probability because either tempTimer or iGUIidMapper are rouge pointers. Can you show us the rest of the code?

McLion

@VRonin
in constructor:

QSignalMapper* iGUIidMapper = new QSignalMapper(this);
connect(iGUIidMapper, SIGNAL(mapped(int)), this, SLOT(HandleGUIloadTimeOut(int)));

.. and in function ..

void QTGUI_MainWindow::HandleGUIloadTimeOut(int iGUIid)
{
  static uint iIsRunning = 0;

  if(iIsRunning & (0x01 << iGUIid))
  { iIsRunning &= ~(0x01 << iGUIid);
    webGUI_loadFinished(false);
  }
  else
  { iIsRunning |= (0x01 << iGUIid);
    QTimer* tempTimer = new QTimer(this);
    tempTimer->setInterval(5000);
    tempTimer->setSingleShot(true);
    GUIidMapper->setMapping(tempTimer, iGUIid);
    connect(tempTimer, SIGNAL(timeout()), GUIidMapper, SLOT(map()));
    connect(tempTimer, SIGNAL(timeout()), tempTimer, SLOT(deleteLater()));
    tempTimer->start();
  }
}

m.sue

You use QSignalMapper* iGUIidMapper in the contructor, so the variable iGUIidMapper is unknown outside of the contructor.

McLion

@m.sue
.. and in *.h
QSignalMapper* iGUIidMapper;
That should do it.

m.sue

@McLion: In the constructor you set the variable (locally) declared in the contructor, but the member variable declared in *.h is still unset.

McLion

@m.sue
Jeeezz... am I blind ?!?
Fixed .. I'll post back once it fully works.
Thanks!

mrjj

@McLion
It's a classic :)
Copy def from .h, add the new part. Forget to remove the type :)

VRonin

btw I don't think I like what you are doing with iIsRunning I think it shouldn't be static (different windows should use different iIsRunning) and it's unnecessarily limited (if iGUIid >31 you have a problem). a QSet<int> to store the iGUIid is much more flexible

McLion

@VRonin
Yep - you're absolutely right. It's unfinished code and currently a draft to start off with a ID range of 1 as a proof of concept.
Will take you input into account - Thanks a lot!