Unable to understand QtConcurrent syntax

npatil15

Hello All,

I'm trying to use QtConcurrent but didn't get it through.

I'm implementing it for making a function to run in a separate thread. And uses QtCouncurrent because there is the possibility of having 20 to 30k threads in an application, so I found this suitable because it manages threads based on the available cores in CPU.
I have already tried QThread, QThreadpool and getting some errors, maybe because I'm not managing it properly.

Please just help me with the following syntax.

struct datalist
    {
        datalist(QString &file, QStringList &groupList)
            : m_file(file)
            , m_groupList(groupList)
        {}
        QString m_file;
        QStringList m_groupList;

    };

typedef QHash<QString, QList<s_DATA>> HashType;

QVector<datalist> dList;
 foreach (QString file, filepaths)
 {
       dList.append(datalist(file, groupList));
 }

foreach (datalist newlist, dList)
 {
            QFuture<HashType> ret = QtConcurrent::run(updateQData, newlist);
        }

HashType updateQData(datalist &dlist)
{
HashType gDATA;
//Some processing here
return gDATA;
}

In above I have tried with the map, mapped, reducemapped, but for everytime get same error.

Here I'm getting many errors as:

D:\iNnotate\dashboard\settings.h:302: error: C3867: 'Settings::updateQData': non-standard syntax; use '&' to create a pointer to member

Can someone please help me with the syntax of proper use of QtCouncurrent.

jsulm

@npatil15 Read "Using Member Functions" in https://doc.qt.io/qt-5/qtconcurrentrun.html
You need to call QtConcurrent::run as

QFuture<HashType> ret = QtConcurrent::run(this, &Settings::updateQData, newlist);

Because updateQData is a method of a class not function.