How far can I go with casting when it comes to the new way how Signal & Slots are connected?

c64zottel

I am trying to get this signal:

signals:
    void joystickConnected( JoystickDevice * joystick, JoystickDeviceConfigurator * configurator );

connected with this slot:

public slots:
    void newInputDeviceDetected( InputDevice * dev, InputDeviceConfigurator * configurator );

JoystickDevice inherits InputDevice publicly and the same goes for *DeviceConfigurator.

When try:

connect(
        & JM_instance,
          static_cast< void (JoystickManager:: *) (InputDevice *, InputDeviceConfigurator *) >
          ( & JoystickManager::joystickConnected ),
          d,           & UserInputManagement_Private::newInputDeviceDetected
    );

The compiler gives me the finger with:

error: invalid static_cast from type ‘void (JoystickManager::*)(JoystickDevice*, JoystickDeviceConfigurator*)’ to type ‘void (JoystickManager::*)(InputDevice*, InputDeviceConfigurator*)’
           static_cast< void (JoystickManager:: *) (InputDevice *, InputDeviceConfigurator *)>(& JoystickManager::joystickConnected),

So, I wonder if it is even possible what am I trying to do?

6thC

I'd say you can go quite far.

https://wiki.qt.io/New_Signal_Slot_Syntax

Completely untested but maybe a lambda connect would *(or may not) help:

QObject::connect(&JM_instance, &JoystickManager::joystickConnected,
    [=]( InputDevice *device, InputDeviceConfigurator *config){
       doSomething(device);
doAnotherThing(config);
        }
    );

c64zottel

@6thC This workaround works nice.

I ended up with this:

connect(
        & JM_instance,
        & JoystickManager::joystickConnected,
          [=] ( InputDevice * device, InputDeviceConfigurator * configurator ) {
                d->newInputDeviceDetected(  device,  configurator );
        }
    );

If no better answer comes up in the next days I will mark your suggestion as solution.

6thC

Excellent! Thanks for letting us know.

Glad that got you moving again, also, no casting required :-)

Eddy

This post is deleted!

VRonin

I don't agree with the answers above, you should not use a lambda here. the problem is just that the compiler does not know JoystickDevice is a InputDevice or JoystickDeviceConfigurator is a InputDeviceConfigurator or both. basically you just have to #include the headers with JoystickDevice and JoystickDeviceConfigurator definition.

c64zottel

@VRonin Unfortunately the code has changed in the meantime.

But I reconstructed it: different names, same story.
It still does not work:

#include "userinputmanagement.h"
#include "userinputmanagement_private.h"
#include "joystickdeviceconfigurator.h"
#include "inputdeviceconfiguratorgate.h"
#include "joystickmanager.h"
#include "joystickdevice.h"
#include "inputdevice.h"

    connect(
        & JM_instance,
          static_cast< void (JoystickManager:: *) (InputDevice *, InputDeviceConfiguratorGate *) >
                          ( & JoystickManager::joystickConnected ),
          d,
        & UserInputManagement_Private::newInputDeviceDetected
        );

From JoystickManager (JM_instance) the signal:

signals:
    void joystickConnected( JoystickDevice *, JoystickDeviceConfigurator * );

The receiving slot in UserInputManagement_Private:

public slots:
    void newInputDeviceDetected( InputDevice * dev, InputDeviceConfiguratorGate * configurator );

Inheritance structure:

class JoystickDeviceConfigurator : public InputDeviceConfiguratorGate
class JoystickDevice             : public InputDevice

And the error:

error: invalid static_cast from type ‘void (JoystickManager::*)(JoystickDevice*, JoystickDeviceConfigurator*)’ to type ‘void (JoystickManager::*)(InputDevice*, InputDeviceConfiguratorGate*)’
                           ( & JoystickManager::joystickConnected ),

Any further ideas?