[solved] emit signal problem error: passing 'const ' as 'this' argument of '' discards qualifiers

ras123

Hi,
I tried to emit signal from a class, given below,
@#include <QValidator>

class BlankCheck : public QValidator
{
Q_OBJECT
public:
explicit BlankCheck(QObject *parent = 0);

private:
State validate(QString &input, int &pos) const;
void fixup(QString &input) const;

signals:
void invalidEntry();
};@

@BlankCheck::BlankCheck(QObject *parent) :
QValidator(parent)
{
}

QValidator::State BlankCheck::validate(QString &input, int &pos) const
{
if(!input.isEmpty())
return Acceptable;
return Intermediate;
}

void BlankCheck::fixup(QString &input) const
{
QMessageBox msg;
msg.setWindowTitle("Invalid Column");
msg.setIcon(QMessageBox::Information);
msg.setText("Colum should not be left blank");
msg.exec();
emit invalidEntry();
return;
}@

And gets the following error,
blankcheck.cpp:24: error: passing 'const BlankCheck' as 'this' argument of 'void BlankCheck::invalidEntry()' discards qualifiers

How to solve the issue?
Thanking You,
Ras

andre

Good question!
"This discussion":http://lists.trolltech.com/qt-interest/2005-09/thread01411-0.html might be interesting for you on this. A good question is raised in it though. A const method should have no side effects. How are you going to guarantee that if you emit a signal and whoever is connected to that can do whatever they want?

ras123

I solved the problem by declaring
@signals:
void invalidEntry() const;@

it works OK