Signal and slot

[jayreddy]

Hii

How can I use a Slot with an argument whenever a push button is clicked

[phillip_Qt]

Hii

How can I use a Slot with an argument whenever a push button is clicked

And what is the argument u r passing in Slot.? if it is bool, then u can use like

connect(pushButton, SIGNAL(clicked ( bool),this, SLOT(slot(bool));

connect(pushButton, SIGNAL(clicked ( bool),this, SLOT(slot(bool));

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[jayreddy]

I want to pass a pointer of a class to the slot not bool or some other type

[squidge]

Then you'll need to create your own SLOT and SIGNAL.

eg.

void mySignal(myClass *c);

void mySignal(myClass *c);

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and then

emit mySignal(myClassPtr);

emit mySignal(myClassPtr);

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in your click slot.

[axeljaeger]

There is big chance that you want to do something strange. Please explain what you want to do and we will help you how to map that to the Qt-way.

Anyway, if you want to get the sender object, check the sender()-function in your slot.

But be warned again: There is only rare cases where this is a good idea and I doubt that you hit one of these.

[T0bi4s]

hi ,

got somehow a similar problem:

my programm should calculate how to place packages on a stack, therefore i created a main_acting_class which actually contains all needed functions, anyway to enter values i got some dialogs and i want to close them, but i can't connect the signals.

I'll show what i mean:

connect(ui_package.pb_ok,SIGNAL(clicked()),this,SLOT(dia_package.accept()));

connect(ui_package.pb_ok,SIGNAL(clicked()),this,SLOT(dia_package.accept()));

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this actually won't work, i don't know why i can't use it like that. i also tried:

connect(ui_package.pb_ok,SIGNAL(clicked()),dia_package,SLOT(accept()));

connect(ui_package.pb_ok,SIGNAL(clicked()),dia_package,SLOT(accept()));

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wasn't a good idea either, so i thought of creating a method which closes the dialogs for me, so i wrote this:

void acting_class::close_dialog(QDialog* d){
    d->accept();
}

void acting_class::close_dialog(QDialog* d){
    d->accept();
}

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connect(ui_package.pb_ok,SIGNAL(clicked()),this,SLOT(close_dialog(dia_package)));

connect(ui_package.pb_ok,SIGNAL(clicked()),this,SLOT(close_dialog(dia_package)));

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but i guess d is in this case no pointer like in c#, so anyone got an idea what i could do about this little problem?

thx
tobi

[axeljaeger]

The second attempt should work and is the way it is supposed to work. Please provide more info what was not working there.

Indeed d IS a pointer.

[T0bi4s]

ok,
the error is:

C:/Users/Tobias/Desktop/Schule/AINF/Diplomarbeit/New01/acting_class.cpp:20: error: no matching function for call to 'acting_class::connect(QPushButton*&, const char*, QDialog&, const char*)'

C:/Users/Tobias/Desktop/Schule/AINF/Diplomarbeit/New01/acting_class.cpp:20: error: no matching function for call to 'acting_class::connect(QPushButton*&, const char*, QDialog&, const char*)'

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and i can't use autocomplete in SLOT(), little wired

[axeljaeger]

The receiver object has to be a pointer to a QObject. Prepend the receiver with & to take the adress of the object and converting object to pointer.

[T0bi4s]

thx mr axel jäger now it works

[jayreddy]

hii..

Even I did the same what you did, passing a pointer of a class as an argument to the slot.
my own class lineedit..
lineedit *t ;

connect (t->temp, SIGNAL(clicked()), this, SLOT(del_tag1(t)));
(temp is pushbutton defined in that class)

But an error saying

Object::connect: No such slot QOlaiTagsWidget::del_tag1(t)

is displaying.


Can you help me regarding this .

Thank You

[axeljaeger]

The arguments of signals and slots are types, not variables.

You passed t which is a variable and not a type.

[jayreddy]

Thank a lot.