Is it possible to use a tuple and a loop for QObject::connect?

Sailanarmo

I was wondering if there was a way to clean up how many lines of code I have in the constructor while dealing with a connect.

I was thinking of having a std::vector<std::tuple<QObject*,std::function<void()>,std::function<void()>>> connections;

Where it would look like this in a private member of a class:

const std::vector<std::tuple<QObject*,std::function<void()>,std::function<void()>>> connections =
{
  std::make_tuple(mySlider, std::bind(&QSlider::sliderReleased,mySlider), std::bind(&Foo::onSliderChanged,this)),
  .
  .
  .
};

However, when I tried this doing:

for (const auto &e : connections)
  connect(std::get<0>(e),SIGNAL(std::get<1>(e)),this,SLOT(std::get<2>(e)));

None of the connections would connect, I would get an error like: No such slot Foo::std::get<1>(e).

I thought it was a clever attempt. And honestly I am just wondering if there is a way to make it look cleaner instead of having 20+ lines eating up my constructor. It would be nice if I could do it this way somehow.

SGaist

Hi,

SIGNAL is a macro. I think you are looking for the new-style connect overload that uses function pointers.

Sailanarmo

@SGaist can you point me out in that direction? I would love to check that out.

kshegunov

https://doc.qt.io/qt-5/signalsandslots.html

The first example of QObject::connect, quite literally.

JKSH

See also https://doc.qt.io/qt-5/signalsandslots-syntaxes.html for a comparison between the old and new connect() syntaxes.