Slot

[Arend]

Hello,

What is wrong with:
menu->addAction("Curve 1",this, SLOT(addGraph(QString("Curve 1"))));

I want to give the function addGraph the argument "Curve 1".

Regards,
Arend

[anda_skoa]

You cannot pass argument values to Signal/Slot connects, the arguments are always provided by the signal and passed to the slot.

In your case, where you have a signal without argument and want the slot to be called with a single string argument, the best way forward is to use QSignalMapper.

Create a QSignalMapper instance and use it as the receiver for addAction(), using SLOT(map()).
Then add a mapping from your action to the desired string and connection the signal mapper's mapped(QString) signal to your slot

Something like this

QSignalMapper *mapper = new QSignalMapper( this );
connect( mapper, SIGNAL(mapped(QString)), this, SLOT(addGraph(QString)) );
 
QAction *action = menu->addAction( "Curve 1", mapper, SLOT(map()) );
mapper->setMapping( action, "Curve 1" );

QSignalMapper *mapper = new QSignalMapper( this );
connect( mapper, SIGNAL(mapped(QString)), this, SLOT(addGraph(QString)) );

QAction *action = menu->addAction( "Curve 1", mapper, SLOT(map()) );
mapper->setMapping( action, "Curve 1" );

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Cheers,
_

[Arend]

Thanks for the quick answer, but how to add a second curve?

[ChrisW67]

Read the docs for QSignalMapper, understand what it is doing, and repeat the mapping exercise for the second, third, fourth, and subsequent signals.

[anda_skoa]

Thanks for the quick answer, but how to add a second curve?

Repeat lines 4 and 5

Cheers,
_

[lordkevin]

Thanks for the post...