'QFutureWatcher' does not name a type

[nulluse]

When I moved declaration of a QFutureWatcher object from a member function (where it was a local variable) to the header (in order to use its finished() signal), it started throwing the error in subject.

a.cpp.cc was:

#include <QtCore>
#include <QFutureWatcher>
#include <QMessageBox>
#include <QCoreApplication>
#include <QtConcurrent>
#include <QFileDialog>
#include "a.h"

a::fn() {
  auto lambda [x, y] (int& i) -> int {return 1;};
  QFutureWatcher<void> fw;
  fw.setFuture(QtConcurrent::map(vec, lambda));
}

a.cpp.cc became:

#include <QtCore>
#include <QFutureWatcher>
#include <QMessageBox>
#include <QCoreApplication>
#include <QtConcurrent>
#include <QFileDialog>
#include "a.h"

a::fn() {
  auto lambda [x, y] (int& i) -> int {return 1;};
  fw.setFuture(QtConcurrent::map(vec, lambda));
}

a.h became:

class a : public QDialog {
    Q_OBJECT
public:
    a();
    virtual ~a();
private:
	QVector<int> vec;
	QRect rect;
	QGraphicsScene *scene; // added the next line:
	QFutureWatcher<void> fw; // -- error on this new line: 'QFutureWatcher' does not name a type
};

I thought that as a.cpp.cc included the Qt headers before including a.h, QFutureWatcher should have been declared on the line where the error is being raised. What am I missing?

[Gerd]

Your a.h file is also used by moc without using your .cc file.
moc produces a cpp-file containing the qobject-related things for your class. When this file is compiled qfuturewatcher is unknown.
Gerd

[nulluse]

Great, but what's the solution? Moving the includes into the a.h file?

[mrjj]

@nulluse said:
Hi
I think you might need
#include <QFutureWatcher>
in the .h file

[nulluse]

Can you clarify if I need to move #include <QFutureWatcher> from .cpp.cc file into .h file, or include it in both?

[mrjj]

@nulluse
hi
you should only need in .h
if cpp.cc file does include that .h