QThread * create(Function &&f)

[Qt_crazyer]

Hello. I want to create a new thread using QThread * create(Function &&f). But I don't know how should transfer parameter. I don't quite understand this parameter-Function &&f. Here is my code.

class a
{
private:
QThread* XferThread;
void XferLoop();
}
a::a
{
XferThread = QThread::create(XferLoop);
}

Parameter list mismatch. Does that have anything to do with member function(XferLoop)?How should I change my code？Thanks for any reply.
VS2015 + Qt5.12 on Windows10.

[SGaist]

Hi,

Based on the documentation of the create method, something like:

// somewhere:
void myFunction(int arg1, int arg2)
{
    qDebug() << Q_FUNC_INFO << arg1 << arg2;
}

// somewhere suitable:
QThread *myThread = QThread::create(myFunction, 12, 30);

[beecksche]

@qt_crazyer

Note: this function is only available when using C++17.

Does VS2015 support C++17?
If yes, did you enabled it with CONFIG+=c++17 in the .pro file?

[Qt_crazyer]

@sgaist
Thanks for your reply.
The example you mentioned is correct. But in my code, XferLoop() is the member function of class a. So it shows the error-Parameter list mismatch. The function XferLoop() calls many private variables of class a.
QThread::create(Function &&f) dosen't need C++17, but the QThread::create(Function &&f, Args &&... args) does.

[beecksche]

@qt_crazyer said in QThread * create(Function &&f):

QThread::create(Function &&f) dosen't need C++17, but the QThread::create(Function &&f, Args &&... args) does.

Sorry my fault!

[VRonin]

a::a
:XferThread(QThread::create(std::bind(&a::XferLoop,this))
{

}

The function XferLoop() calls many private variables of class a.

hic sunt leones. Be very careful not to create race conditions

[AshkanV]

You can also use a lambda which is preferred over std::bind:

a::a():
XferThread(QThread::create([this](){XferLoop();})
{}

[kshegunov]

@AshkanV said in QThread * create(Function &&f):

which is preferred over std::bind

One of them catch-all phrases, eh? Says who, and why is it supposedly preferred?

[Christian Ehrlicher]

@kshegunov https://clang.llvm.org/extra/clang-tidy/checks/modernize-avoid-bind.html :)

[kshegunov]

Okay, so I found out about the "who". Now if you can convince me that "it is preferred" is the same as "clang tidy says it's preferred" ...
I remember there was this one guy who said everything should be auto because reasons. Recently there was this other guy (here) that didn't realize using auto broke his code ... stuff happens, I guess ...

[Christian Ehrlicher]

@kshegunov said in QThread * create(Function &&f):

Now if you can convince me that "it is preferred" is the same as "clang tidy says it's preferred" ...

No, no need to convince you. :)
I prefer lambdas because I never understood std::bind() and I need to think about it every time I see such a call :)

[kshegunov]

@Christian-Ehrlicher said in QThread * create(Function &&f):

I prefer lambdas

Such reasoning I can live with, even without any justification. I just grumble at the catch-it-all-no-need-to-think-about-it sort of statement(s).