[Kde-perl] Overloading of Qt::ToolTip::maybeTip doesn't work

Ole Christensen Ole.Christensen at web.de
Fri Oct 29 08:16:39 CEST 2004

Please find attached tooltip.pl which should do as a shrinked down test 

If you leave the virtual debugging channel switched on, you can see the 
said messages 1 second after you push the mouse into the white listview 

Appearently the mapObject NEVER gets called throughout the program. But 
maybe there is something wrong with the setup on my machine???

Best regards,


Richard Dale wrote:
> On Thursday 28 October 2004 21:14, Ole Christensen wrote:
>>unfortunately the patch you suggested does not fix the problem.
>>Everything unchanged. Find the corresponding output below. Note the "--
>>Ole" ;-) So the right lib actually gets used. The mapObject function
>>obviously does not get called at all in this context. I put an fprintf
>>there which is not reached.
> mapObject() should get called when the instance of Qt::ToolTip is created. 
> These two lines look for the instance in the map before trying to call the 
> virtual method:
>  SV *obj = getPointerObject(ptr);
>  smokeperl_object *o = sv_obj_info(obj);
> If it isn't found, you get the 'Cannot find object.. ' error.
>>virtual 0x8746220->QToolTip::maybeTip() called
>>Cannot find object for virtual method -- Ole
>>I applied the patch on a fresh cvs export from sourceforge. Is there
>>anything else I could do to track down the problem? Thanks in any case
>>for your help.
> Can you post the source of a test program to make it possible to reproduce the 
> problem? You can add 'use Qt::debug qw( gc );' at the top of your program, to 
> produce a debugging trace of the garbage collection and C++ to perl instance 
> mapping.
> -- Richard
>>Richard Dale wrote:
>>>On Wednesday 27 October 2004 22:48, Ole Christensen wrote:
>>>>I am trying to implement a dynamic tooltip. The problem is that
>>>>overloading Qt::ToolTip::maybeTip does not work for me. I already have
>>>>reimplemented virtual functions in perl, but for some reason it does not
>>>>work for maybeTip. QToolTip is not a subclass of QObject. Does that
>>>>When I switch on debugging of virtual functions I get:
>>>>virtual 0x8772ea0->QToolTip::maybeTip() called
>>>>Cannot find object for virtual method
>>>>I am using
>>>>PerlQt 3.008
>>>>Qt 3.3.3
>>>>perl 5.8.2
>>>I had the same problem as this with qtruby. Here is the entry from the
>>>qtruby ChangeLog:
>>> * If a class doesn't have a virtual destructor, then no mapping was
>>>being kept from the C++ instance to the corresponding ruby value. If the
>>>class had virtual method callbacks, this meant that the ruby instance
>>>couldn't be found, and the callback couldn't be made.
>>> * Hence, the Qt::ToolTip callback in examples/qt-examples/tooltip didn't
>>>   work, as that class doesn't have a virtual destructor.
>>>For PerlQt, you would need to remove this test from the mapObject()
>>>function in Qt.xs:
>>>    if(!c.hasVirtual() ) {
>>>    }
>>>    SV *obj
>>>    CODE:
>>>    smokeperl_object *o = sv_obj_info(obj);
>>>    if(!o)
>>>        XSRETURN_EMPTY;
>>>    SmokeClass c( o->smoke, o->classId );
>>>//    if(!c.hasVirtual() ) {
>>>//    }
>>>    mapPointer(obj, o, pointer_map, o->classId, 0);
>>>So that a mapping of the pointer from a C++ instance to a perl instance
>>>is always kept.
>>>-- Richard
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