Qt-interest Archive, December 2007
is it possible to have signals as defines ?
Message 1 in thread
having this:
#define ADD_LOG_FEATURES \
signals: \
void emitLogInfo( QString infoMessage ); \
void emitLogWarning( QString warningMessage ); \
void emitLogError( QString errorMessage ); \
void emitLogFatal( QString fatalMessage );
I have a class where I do this:
class MyCalss : public QCoreApplication
{
Q_OBJECT
ADD_LOG_FEATURES
public:
MyClass( int argc, char** argv );
~MyClass();
........
};
And as a result I get this:
out/myclass.o(.gnu.linkonce.t._ZN3MyClass7logInfoE7QString+0x22): In
function `bool operator< <QString, unsigned short>(QPair<QString,
unsigned short> const&, QPair<QString, unsigned short> const&)':
/usr/home/nicu/qt/debug-shared-sql-plugin/include/QtCore/qstring.h:791:
undefined reference to `MyClass::emitLogInfo(QString)'
*** Error code 1 (continuing)
/usr/home/nicu/qt/debug-shared-sql-plugin/include/QtCore/qstring.h
undefined reference to `MyClass::emitLogInfo(QString)'
Any ideas ?
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Message 2 in thread
On 08.12.07 22:26:14, Yong Taro wrote:
> having this:
No thats not possible, moc doesn't support macro's and moc is the app
that create the code for the signal-functions.
Andreas
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Message 3 in thread
> #define ADD_LOG_FEATURES \
> signals: \
> void emitLogInfo( QString infoMessage ); \
> void emitLogWarning( QString warningMessage ); \
> void emitLogError( QString errorMessage ); \
> void emitLogFatal( QString fatalMessage );
Wouldn't you be better off creating a pure virtual "log" class and
inheriting from that so that you get the signals for "free"?
A
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Message 4 in thread
On søndag den 9. December 2007, Adam Hawes wrote:
> > #define ADD_LOG_FEATURES \
> > signals: \
> > void emitLogInfo( QString infoMessage ); \
> > void emitLogWarning( QString warningMessage ); \
> > void emitLogError( QString errorMessage ); \
> > void emitLogFatal( QString fatalMessage );
Change this to
enum LogLevel { Info, Warning, Error, Fatal };
signals:
void emitLog( LogLevel level, const QString& infoMessage );
This way you at least only have to implement one method, and if you add new
log levels they will automatically be supported. You can put the enum in some
shared class or namespace.
Always change the specs instead of following them blindly, when there is an
implementation detail that wasn't thought of when the specs were made.
> Wouldn't you be better off creating a pure virtual "log" class and
> inheriting from that so that you get the signals for "free"?
You can't create a pure virtual class that has signals or slots. The
declaration of these includes creation of methods and subclassing QObject.
However, you might use interfaces. Search for Q_INTERFACES in assistant for a
description on how to do this. It's intended for plugins, but I don't see why
it wouldn't work here as well.
Bo.
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