Re: [Qt-creator] Connecting signals from child thread with slots in main thread
Message de Soumen banerjee : > hi, > thaks for all the help, ill check it out. actually im kinda new to Qt > and C++ having extensively used PyQt before. and why is it the wrong > forum to post this in? where do i post it then? Hi, This list is for questions related to QtCreator. For questions regarding Qt, the following list is more suitable: Qt-interest mailing list qt-inter...@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-interest Regards, Gilles ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
hi, thaks for all the help, ill check it out. actually im kinda new to Qt and C++ having extensively used PyQt before. and why is it the wrong forum to post this in? where do i post it then? regards, soumen ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
On Dec 6, 2009, at 12:48 PM, ext Soumen banerjee wrote: > In the files attached, mainwindow.cpp has the following line > > connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); > > where ptr is of type mythread* which is derived from QThread > the application compiles without error but on running, quits with > segfault. Omitting the connect line solves the problem but removes all > the functionality. How do you connect these together? > Regards > Soumen You don't give "ptr" a value before calling "connect". Moving "ptr=new mythread(this);" before the "connect" statement (or something similar) should do it for you. -- Eike Ziller Software Engineer Nokia, Qt Development Frameworks Phone +49 (0)30 6392 3255 Fax+49 (0)30 6392 3256 E-mail eike.zil...@nokia.com ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
This is also the wrong forum to be posting this in. On Sun, Dec 6, 2009 at 10:41 AM, Danny Price wrote: > Even so, the pointer should have been initialised to 0 or NULL in the > initializer list. Leaving pointers to contain junk is never a good idea. > > On 6 Dec 2009, at 17:59, Gilles Valette wrote: > > > Message de Danny Price : > > > >> Always use initializer lists. > >> > > > > He can't because this call is not made in a constructor but in a slot > > corresponding to a button click, and a new thread is created at each > > click. I am not saying that it is the best way to do it (I actually do > > not know the goal of the code...), I was just answering to the > > question about the segfault in the given code. > > > > Regards, > > > > Gilles > > > >> On 6 Dec 2009, at 13:39, Gilles Valette wrote: > >> > >>> Message de Soumen banerjee : > >>> > In the files attached, mainwindow.cpp has the following line > > connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); > > where ptr is of type mythread* which is derived from QThread > the application compiles without error but on running, quits with > segfault. Omitting the connect line solves the problem but removes all > the functionality. How do you connect these together? > Regards > Soumen > > >>> > >>> Hi, > >>> > >>> In mainwindow.cpp when you call connect, ptr is undefined, causing the > >>> segfault. > >>> > >>> Putting the two lines in this order solves the problem : > >>> > >>>ptr=new mythread(this); > >>>connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); > >>> > >>> Hope this helps. > >>> > >>> Gilles > >>> > >>> > >>> ___ > >>> Qt-creator mailing list > >>> Qt-creator@trolltech.com > >>> http://lists.trolltech.com/mailman/listinfo/qt-creator > >> > >> ___ > >> Qt-creator mailing list > >> Qt-creator@trolltech.com > >> http://lists.trolltech.com/mailman/listinfo/qt-creator > >> > >> > > > > > > > > -- > > Gilles VALETTE - PhD > > Maître de conférences en informatique - IUT de Reims > > Université de Reims Champagne-Ardenne (URCA) - CReSTIC EA3804 > > Rue des Crayères, BP 1035 51687 Reims Cedex 2 (France) > > Tel: +33 (0)3 26 91 84 58 > > http://www.crestic.univ-reims.fr/fiche.php?id=216 > > > > > > > > ___ > > Qt-creator mailing list > > Qt-creator@trolltech.com > > http://lists.trolltech.com/mailman/listinfo/qt-creator > > > ___ > Qt-creator mailing list > Qt-creator@trolltech.com > http://lists.trolltech.com/mailman/listinfo/qt-creator > ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
Even so, the pointer should have been initialised to 0 or NULL in the initializer list. Leaving pointers to contain junk is never a good idea. On 6 Dec 2009, at 17:59, Gilles Valette wrote: > Message de Danny Price : > >> Always use initializer lists. >> > > He can't because this call is not made in a constructor but in a slot > corresponding to a button click, and a new thread is created at each > click. I am not saying that it is the best way to do it (I actually do > not know the goal of the code...), I was just answering to the > question about the segfault in the given code. > > Regards, > > Gilles > >> On 6 Dec 2009, at 13:39, Gilles Valette wrote: >> >>> Message de Soumen banerjee : >>> In the files attached, mainwindow.cpp has the following line connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); where ptr is of type mythread* which is derived from QThread the application compiles without error but on running, quits with segfault. Omitting the connect line solves the problem but removes all the functionality. How do you connect these together? Regards Soumen >>> >>> Hi, >>> >>> In mainwindow.cpp when you call connect, ptr is undefined, causing the >>> segfault. >>> >>> Putting the two lines in this order solves the problem : >>> >>>ptr=new mythread(this); >>>connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); >>> >>> Hope this helps. >>> >>> Gilles >>> >>> >>> ___ >>> Qt-creator mailing list >>> Qt-creator@trolltech.com >>> http://lists.trolltech.com/mailman/listinfo/qt-creator >> >> ___ >> Qt-creator mailing list >> Qt-creator@trolltech.com >> http://lists.trolltech.com/mailman/listinfo/qt-creator >> >> > > > > -- > Gilles VALETTE - PhD > Maître de conférences en informatique - IUT de Reims > Université de Reims Champagne-Ardenne (URCA) - CReSTIC EA3804 > Rue des Crayères, BP 1035 51687 Reims Cedex 2 (France) > Tel: +33 (0)3 26 91 84 58 > http://www.crestic.univ-reims.fr/fiche.php?id=216 > > > > ___ > Qt-creator mailing list > Qt-creator@trolltech.com > http://lists.trolltech.com/mailman/listinfo/qt-creator ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
Message de Danny Price : > Always use initializer lists. > He can't because this call is not made in a constructor but in a slot corresponding to a button click, and a new thread is created at each click. I am not saying that it is the best way to do it (I actually do not know the goal of the code...), I was just answering to the question about the segfault in the given code. Regards, Gilles > On 6 Dec 2009, at 13:39, Gilles Valette wrote: > >> Message de Soumen banerjee : >> >>> In the files attached, mainwindow.cpp has the following line >>> >>> connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); >>> >>> where ptr is of type mythread* which is derived from QThread >>> the application compiles without error but on running, quits with >>> segfault. Omitting the connect line solves the problem but removes all >>> the functionality. How do you connect these together? >>> Regards >>> Soumen >>> >> >> Hi, >> >> In mainwindow.cpp when you call connect, ptr is undefined, causing the >> segfault. >> >> Putting the two lines in this order solves the problem : >> >> ptr=new mythread(this); >> connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); >> >> Hope this helps. >> >> Gilles >> >> >> ___ >> Qt-creator mailing list >> Qt-creator@trolltech.com >> http://lists.trolltech.com/mailman/listinfo/qt-creator > > ___ > Qt-creator mailing list > Qt-creator@trolltech.com > http://lists.trolltech.com/mailman/listinfo/qt-creator > > -- Gilles VALETTE - PhD Maître de conférences en informatique - IUT de Reims Université de Reims Champagne-Ardenne (URCA) - CReSTIC EA3804 Rue des Crayères, BP 1035 51687 Reims Cedex 2 (France) Tel: +33 (0)3 26 91 84 58 http://www.crestic.univ-reims.fr/fiche.php?id=216 ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
Always use initializer lists. On 6 Dec 2009, at 13:39, Gilles Valette wrote: > Message de Soumen banerjee : > >> In the files attached, mainwindow.cpp has the following line >> >> connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); >> >> where ptr is of type mythread* which is derived from QThread >> the application compiles without error but on running, quits with >> segfault. Omitting the connect line solves the problem but removes all >> the functionality. How do you connect these together? >> Regards >> Soumen >> > > Hi, > > In mainwindow.cpp when you call connect, ptr is undefined, causing the > segfault. > > Putting the two lines in this order solves the problem : > > ptr=new mythread(this); > connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); > > Hope this helps. > > Gilles > > > ___ > Qt-creator mailing list > Qt-creator@trolltech.com > http://lists.trolltech.com/mailman/listinfo/qt-creator ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
Re: [Qt-creator] Connecting signals from child thread with slots in main thread
Message de Soumen banerjee : > In the files attached, mainwindow.cpp has the following line > > connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); > > where ptr is of type mythread* which is derived from QThread > the application compiles without error but on running, quits with > segfault. Omitting the connect line solves the problem but removes all > the functionality. How do you connect these together? > Regards > Soumen > Hi, In mainwindow.cpp when you call connect, ptr is undefined, causing the segfault. Putting the two lines in this order solves the problem : ptr=new mythread(this); connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); Hope this helps. Gilles ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
[Qt-creator] Connecting signals from child thread with slots in main thread
In the files attached, mainwindow.cpp has the following line connect(ptr,SIGNAL(setlabel(int)),this,SLOT(setLabel(int))); where ptr is of type mythread* which is derived from QThread the application compiles without error but on running, quits with segfault. Omitting the connect line solves the problem but removes all the functionality. How do you connect these together? Regards Soumen mainwindow.cpp Description: Binary data mainwindow.h Description: Binary data mainwindow.ui Description: Binary data thread.cpp Description: Binary data thread.h Description: Binary data Thread.pro Description: Binary data ui_mainwindow.h Description: Binary data ___ Qt-creator mailing list Qt-creator@trolltech.com http://lists.trolltech.com/mailman/listinfo/qt-creator
