Simple question about QtConcurrent

Hi,

I've the following question:

Why don't we be able to use a member function jointly with QtConcurrent or QThread? Why must be a standalone function?

Thanks

It can be a member function as well but it has to be a member function of a class that is carried in the container passed to QtConcurrent. Otherwise than that only static member functions and non-member functions may be used. This is caused by the fact that it is not possible to specify a "pointer to a function of any class" in C++.

Hi Wysota,

Thanks a lot, now I understand.

Bye

I am not sure if I understood the OP's question correctly.

You can use member functions for some things, e.g. with QtConcurrent::mapped, if you wrap them with Boost.Bind or something similar.

Example from Qt docs:

Code:

---

QList<QImage> images = ...;
QFuture<QImage> thumbnails = QtConcurrent::mapped(images, boost::bind(&QImage::scaledToWidth, 100 Qt::SmoothTransformation));

---

HTH

Hi Caduel,

yes something as:

class TEST
{
public:
TESTE();

void funct();
};

TESTE test;
QList<QImage> images = ...;
QFuture<QImage> thumbnails = QtConcurrent::mapped(images, test.funct(&QImage::scaledToWidth, 100 Qt::SmoothTransformation));

Now I understand that isn't possible. I must be use static functions for example.
Like the Wysota explained me

your example is confusing... a function returning void does not make sense with "mapping".

Code:

---

class TEST
{
public:
  TESTE();
 
  QImage funct(const QString&);
};
 
TESTE test;
QLis<QString> files = ...;
QFuture<QImage> pics = QtConcurrent::mapped(files, boost::bind(&TEST::func, &test));

---

something like that should work. (Haven't tried it.)

Sorry,

I know about this.
Your example this ok.


Thanks for your help