Qt slot with default argument

Question

I have a block of spin controls which change individual elements of an array Rather than having separate receiver slot functions, I wanted to just specify which control sent the message in the signal

You can do this with a QSignalMapper - but is there anyway of doing it simply as below?

spin0 = new QDoubleSpinBox;
connect(spin0,SIGNAL(valueChanged(double)),this,SLOT(handler(0,double));

spin1 = new QDoubleSpinBox;
connect(spin1,SIGNAL(valueChanged(double)),this,SLOT(handler(1,double));
....

private slot:
void handler(int element,double value);

Answer 1

From any slot handler you can can use sender() to get a pointer to the object that sent the signal. Then you can use the objectName() property to communicate any further identifying information.

Answer 2

I don't believe so, at least not using that syntax ... the SIGNAL and SLOT macros turn their arguments into strings which are then parsed and used by the Qt runtime to look-up the associated functions and/or class methods in the tables created by moc during the pre-processing phase of compilation. So if you encoded a default argument into the SLOT macro, then that's not a valid function signature that can be used by Qt for run-time lookup of the actual slot function in the moc -generated function tables.