Slot - Signal with parameter

[Lodhart]

Hi, can you help me, please...

i have..


for(x) ( QPushButton * pb = new QPushButton; ... )

x - is 5x or 15x, ... but when i click on button, how i can know which button was pressed ?..
some example will help me..

[squidge]

QSignalMapper:



for (...) {
QPushButton *button = new QPushButton(...);
connect(button, SIGNAL(clicked()), signalMapper, SLOT(map()));
signalMapper->setMapping(...);
}

connect(signalMapper, SIGNAL(mapped(argtype)), this, SIGNAL(clicked(argtype)));


argtype can be int, QString, anything supported by QSignalMapper

[Lodhart]

thank you for quick reply ;-)

[rajesh]

Use Sender()
eg: Button *clickedButton = qobject_cast<Button *>(sender());


void Calculator::unaryOperatorClicked()
{
Button *clickedButton = qobject_cast<Button *>(sender());
QString clickedOperator = clickedButton->text();
double operand = display->text().toDouble();
double result = 0.0;

if (clickedOperator == tr("Sqrt")) {
if (operand < 0.0) {
abortOperation();
return;
}
result = sqrt(operand);
} else if (clickedOperator == tr("x\262")) {
result = pow(operand, 2.0);
} else if (clickedOperator == tr("1/x")) {
if (operand == 0.0) {
abortOperation();
return;
}
result = 1.0 / operand;
}
display->setText(QString::number(result));
waitingForOperand = true;
}

[squidge]

sender() violates the object-oriented principle of modularity, which is why you should not use it unless there's no alternative (and in this case, there is).

In your example, you could remove 'clickedButton' from your code completely, and have 'clickedOperator' passed to it as a parameter, which is much more readable.

[Lodhart]

Hi a have a new problem...
when i want change properties of created button, program go to run-time error.


void create () (
for (...) QPushButton * b = new QPushButton;
Struct.b[Struct.top++]=b;
)

theStruct is declare in class MainWindow in public. And in othe fun.:


Struct.b[..]->setText("change");

[Tanuki-no Torigava]

Hi, look at the calc example bundled with Qt in examples. Looks like your case.

Cheers,
-- tanuki

[pipapongo]

thanks again but i dont get it just yet...

all the widgets have to know about the myData Object in MainWindow. so is it better to solve this by Singleton or do i give all the widgets a reference to my Data in the constructor, Or is there another way how it should be done?



class myMessage : public QObject
{
Q_OBJECT
public:
myMessage(QObject *parent = 0,myData*);
public slots:
void showMesssage();
void showMesssage(QString *s);
void newMeesageText(QString *s);
private:
QMessageBox *message;

};
//and in MainWIndow i make:
myData * data;
myMessage *mess(this,data);

in that way all the widgets have the pointer to the data in themselve and i i update it in another widget the changes are accessable

I hope you get my question

thank

[Santosh Reddy]

Post does not make any sense in this thread