How does a function in Qt accept passed arguments from two places? - c++

Question

I want to wirte a funtion CH1_Hard_Soft to process data, which accepts two arguments from two different function.
double MainWindow::getdata_CH1(double time)
{
...
double CH1_data=0;
switch (CH1.Source) {
case 0: //software-hard
CH1_data = CH1_Hard_Soft(time);
....
}
The function CH1_Hard_Soft need to accept an argument time from getdata_CH1 and accept a QVector from other thread. And the function CH1_Hard_Soft will process these data and then return a QVector to getdata_CH1(double time). I don't know how to do this. Please give me some suggestions on how to do this.THANKS!!!

Answer 1

You can use a Function Object: create a new class with two attributes (one per parameter). Create setter for each parameter (or redefine the operator () to be closer to the behavior of a real function).
Each setter should check if the others are setted also. In that case, call you algorithm and send the result with a signal.
For example:
A simple worker executed in another thread. It will send fake data after 3 seconds
class Worker: public QObject
{
Q_OBJECT
public:
Worker(): QObject()
{
}
void timerEvent(QTimerEvent* ev)
{
qDebug() << Q_FUNC_INFO;
emit getVector(QVector<int>() << 2 << 4 << 6 << 8);
killTimer(timerId);
}
public slots:
void run()
{
timerId = startTimer(3000);
}
signals:
void getVector(QVector<int> const& vec);
private:
int timerId;
};
The Function Object: it will accept two param (a double and a vector)
// For convenience. Define a value and a flag to check if the value is well set
template<typename T> struct Param
{
T value;
bool isInit;
Param(): isInit(false)
{}
void setValue(T const& v)
{
value = v;
isInit = true;
}
};
// The processor
class Processor: public QObject
{
Q_OBJECT
public:
Processor(QObject* parent=nullptr): QObject(parent)
{}
void operator()(QVector<int> const& vector)
{
values.setValue(vector);
if (time.isInit)
process();
}
void operator()(double t)
{
time.setValue(t);
if (values.isInit)
process();
}
signals:
void done(double result);
private:
// Will be called as soon as all the parameters are set
void process()
{
// DO something
qDebug() << Q_FUNC_INFO;
emit done(time.value * values.value.length());
}
Param<QVector<int> > values;
Param<double> time;
};
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
// Run the thread
Worker* worker = new Worker();
QThread* th = new QThread();
worker->moveToThread(th);
QObject::connect(th, &QThread::started, worker, &Worker::run);
Processor CH1_Hard_Soft;
// Will be called when the CH1_Hard_Soft will send its result
QObject::connect(&CH1_Hard_Soft, &Processor::done, [=](double result) { qDebug() << "RESULT" << result; });
// Set the param vector
QObject::connect(worker, &Worker::getVector, [&](QVector<int> const& vec) { CH1_Hard_Soft(vec); });
// Call CH1_Hard_Soft with the first param
double time = 12.6;
CH1_Hard_Soft(time);
th->start();
return app.exec();