Signals and Slots in dll

[ankurjain]

hi,
can anybody tell me if i can use signals and slots in dll ??

i wrote a dll. in it there is a function that creates context menu, function that adds action (cut, copy, paste) to it, functions to implement the actions.
i connected the via signals and slots the functions called on clicking the actions.

But i can't see the effect.

please help and clarify.

[high_flyer]

if you have QObjects in your dll you can use signal slots.

[ankurjain]

i have to connect a QAction Object (deleteAct) and QGrid inherited from QTableWidget Object (table).

On click of a context menu item this slot must be executed.
my dll is making a table in the target project.

connect(deleteAct,SIGNAL(triggered()),this,SLOT(de leteRow()))

is this right ??

[niko]

if both classes inherit from QObject and have the Q_OBJECT-macro it should work.

you could probalby first link it directly into the executable - and then try creating the dll....

[ankurjain]

hi,
i hav implemented signals and slots in dll.

now if i am importing the dll in my project, it gives errors and warnings as follows :

xxx : warning C4273: 'public: static struct QMetaObject const QGrid::staticMetaObject' : inconsistent dll linkage.  dllexport assumed.
xxx  : error C2491: 'QGrid::staticMetaObject' : definition of dllimport static data member not allowed
xxx  : warning C4273: 'metaObject' : inconsistent dll linkage.  dllexport assumed.
xxx  : warning C4273: 'qt_metacast' : inconsistent dll linkage.  dllexport assumed.
xxx   : warning C4273: 'qt_metacall' : inconsistent dll linkage.  dllexport assumed.

xxx : warning C4273: 'public: static struct QMetaObject const QGrid::staticMetaObject' : inconsistent dll linkage.  dllexport assumed.
xxx  : error C2491: 'QGrid::staticMetaObject' : definition of dllimport static data member not allowed
xxx  : warning C4273: 'metaObject' : inconsistent dll linkage.  dllexport assumed.
xxx  : warning C4273: 'qt_metacast' : inconsistent dll linkage.  dllexport assumed.
xxx   : warning C4273: 'qt_metacall' : inconsistent dll linkage.  dllexport assumed.

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if i remove signals and slots then it compiles fine .... what to do to remove the error.

[ChristianEhrlicher]

hi,
if i remove signals and slots then it compiles fine .... what to do to remove the error.

Define your DLL_EXPORT - macro in the correct way.

#ifdef MAKE_YOUR_DLL
# define YOUR_DLL_EXPORT Q_DECL_EXPORT
#else
# if Q_CC_MSVC
#  define YOUR_DLL_EXPORT Q_DECL_IMPORT
# else
#  define YOUR_DLL_EXPORT
# endif
#endif

#ifdef MAKE_YOUR_DLL
# define YOUR_DLL_EXPORT Q_DECL_EXPORT
#else
# if Q_CC_MSVC
#  define YOUR_DLL_EXPORT Q_DECL_IMPORT
# else
#  define YOUR_DLL_EXPORT
# endif
#endif

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[ankurjain]

thanx for replying christian,
but the same error persists.

i don know why ... is there some error in import/export

my code goes as :

#ifdef Q_OS_WIN
#ifdef BUILD_QGRID
# define QGRID_EXPORT Q_DECL_EXPORT
#else
#  define QGRID_EXPORT Q_DECL_IMPORT
#endif
# else
#  define QGRID_EXPORT
# endif

#ifdef Q_OS_WIN
#ifdef BUILD_QGRID
# define QGRID_EXPORT Q_DECL_EXPORT
#else
#  define QGRID_EXPORT Q_DECL_IMPORT
#endif
# else
#  define QGRID_EXPORT
# endif

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i tried ur code ... i gives error :

fatal error C1017: invalid integer constant expression

fatal error C1017: invalid integer constant expression

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i changed
#if QT_CC_MSVC to #ifdef QT_CC_MSVC

it gave same error as earlier ..

xxx : warning C4273: 'public: static struct QMetaObject const QGrid::staticMetaObject' : inconsistent dll linkage.  dllexport assumed.
xxx : error C2491: 'QGrid::staticMetaObject' : definition of dllimport static data member not allowed
xxx : warning C4273: 'metaObject' : inconsistent dll linkage.  dllexport assumed.
xxx : warning C4273: 'qt_metacast' : inconsistent dll linkage.  dllexport assumed.
xxx : warning C4273: 'qt_metacall' : inconsistent dll linkage.  dllexport assumed.

xxx : warning C4273: 'public: static struct QMetaObject const QGrid::staticMetaObject' : inconsistent dll linkage.  dllexport assumed.
xxx : error C2491: 'QGrid::staticMetaObject' : definition of dllimport static data member not allowed
xxx : warning C4273: 'metaObject' : inconsistent dll linkage.  dllexport assumed.
xxx : warning C4273: 'qt_metacast' : inconsistent dll linkage.  dllexport assumed.
xxx : warning C4273: 'qt_metacall' : inconsistent dll linkage.  dllexport assumed.

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[ChristianEhrlicher]

It is Q_CC_MSVC and not QT_CC_MSVC
You maybe have not set BUILD_QGRID when building your dll (as the error states you're using dllimport == Q_DECL_IMPORT).
Please read about importing / exporting symbols in your favorite msvc book / at msdn.mcrosoft.com

[ankurjain]

Sorry my mistake (Q and QT misspell),

i defined BUILD_QGRID in .pro file as DEFINES += BUILD_QGRID
also it shows in the project settings as /D "BUILD_QGRID"

the problem is due to the Q_OBJECT directive.

if i comment the line and the slots in the class it works fine.

also the error is stating "definition of dllimport static data member not allowed"

and warnings regarding exporting. i didn't got these errors.

is there some other way to define the BUILD_QGRID, like in the cpp file ?