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

[Ole Christensen]

Richard,

I have investigated the thing a little bit more. The problem was that I 
used the latest CVS export. mapObject actually isn't called in this 
version any more. Tracking down the CVS logs I found that Germain Garand 
has removed two calls to mapObject in Qt.pm version 1.86. The log holds 
"don't map objects twice". Maybe one deletion happened unintentionally. 
I have no idea.

http://cvs.sourceforge.net/viewcvs.py/perlqt/PerlQt-3/PerlQt/Qt.pm?r1=1.85&r2=1.86

Your patch applied to 3.008 seems to work fine for me. Thanks a lot. An 
appropriate fix should also go into CVS if there is no serious drawback. 
Even if Qt-4 is scheduled to have a virtual destructor for QToolTip, 
which should solve the problem anyway as far as I have understood.


Regards,

Ole.


Richard Dale wrote:
> On Thursday 28 October 2004 21:14, Ole Christensen wrote:
> 
>>Richard,
>>
>>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:
>>>
>>>>Hi,
>>>>
>>>>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
>>>>matter?
>>>>
>>>>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() ) {
>>> XSRETURN_EMPTY;
>>>    }
>>>
>>>void
>>>mapObject(obj)
>>>    SV *obj
>>>    CODE:
>>>    smokeperl_object *o = sv_obj_info(obj);
>>>    if(!o)
>>>        XSRETURN_EMPTY;
>>>    SmokeClass c( o->smoke, o->classId );
>>>//    if(!c.hasVirtual() ) {
>>>// XSRETURN_EMPTY;
>>>//    }
>>>    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.