On Monday 05 August 2013 23:15:00 Thomas Lübking wrote: > On Montag, 5. August 2013 22:32:48 CEST, Jan Kundrát wrote: > > On Monday, 5 August 2013 19:54:05 CEST, Thomas Lübking wrote: > >> Did i miss this? > >> Where's mentioned "does not work" (reason is perhaps > >> lacking Q_OBJECT macro?) > > > > From pali-gsoc-merge:src/Common/PluginLoader.cpp: > >> // NOTE: qobject_cast not working when trojita is compiled > >> as shared > > > > library, dynamic_cast working fine > > Ok, i'll open bets. > > ---------- > > Pali, did you figure this trying on the NullPlugins? > > ---------- > > On a general note and particular on this case (which i missed > because after understanding it's just for development testing > i rather skipped them): > > Placing "O_OBJECT" into a source file (*.cpp) does *NOT* work, > the MOC does not (easily - and I don't see that in > CMakeLists.txt and NO: just write a header ;-) proceed them, > thus there's no MetaObject processing and thus there's no > qobject_cast'ing to that particular type. > > Signals and slots of the base class will of course continue to > work, but it's not possible to add new ones or shadow the > present. > > dynamic_cast might actually work on gcc, but that's due to > some gcc magic and particular linker calls on symbol exports > - it's absolutely not reliable. > > In general dynamic_casting across libraries does *not* work - > if you want to do this (outside Qt happyland), you add some > nice hints (eg. a type id) on the actual type and then just > static_cast them according to the type (and then you can cast > down to determine the patch - or you just move to Qt > happyland =) > > To hook onto that: > iirc you required Trojitá -fPIC for kontact inclusion: was > there a particular reason (from kontact side) or just because > (you?) tuned up GCC parameters until dynamic_cast'ing worked > in order to make trojitá a shared library. > > Cheers, > Thomas
Trojita executable binary consists of more static linked libraries (Common, Gui, ...). By default static linked libraries (cmake on linux) are not compiled as position independent. It is OK for executables, because these are also not position independent. But shared dynamic libraries must be position independent, because dynamic loader loading them to address which is not known at compile time. And you cannot create shared library from non position independent objects/libraries. Kontact plugin is shared library and if I want to reuse compiled trojita code (all static linked libraries), I need to compile them as position independent (gcc -fPIC flag). Problem with qobject_cast I already wrore in mail with subject "GSoC: plugins & loader". Problem is: When trojita is started in normal standalone mode, everything working fine. If trojita is stared as kontact plugin, qobject_cast from QObject returned from *any* plugin (not only null plugins) to PasswordInterface or AddressbookInterface returning NULL. And I do not know why it is not working. Maybe it is because of Common? Can you try to compile plugins, compile kontact part, change dynamic_cast with qobject_cast and test if trojita from kontact can load plugins on your test machine? I'd like to know if I have something broken, or not. -- Pali Rohár pali.ro...@gmail.com
signature.asc
Description: This is a digitally signed message part.
