Disconnect/Connect using RAII paradigm

enne9

Hello, I would like to use RAII paradigm for operations involving disconnect and then connect.
In the following, an example of what I have:

disconnect(sender, signal, receiver, method);
// Do something
connect(sender, signal, receiver, method);

or even

disconnect(sender, signal, receiver, method);
disconnect(sender2, signal2, receiver2, method2);
// Do something
connect(sender, signal, receiver, method);
connect(sender2, signal2, receiver2, method2);

This is motivated by the fact that the code in the middle would otherwise send a signal, that I don't want to emit.

Is there any clean way to write the same using RAII paradigm? Something like:

TemporaryDisconnect(sender, signal, receiver, method, []{
  doSomething();
});

I don't have much experience so I was trying with:

template <typename PointerToMemberFunction>
class TemporaryDisconnect : public QObject {
  const QObject *sender, *receiver;
  PointerToMemberFunction signal, method;

  TemporaryDisconnect(const QObject *sender, PointerToMemberFunction signal,
                      const QObject *receiver, PointerToMemberFunction method,
                      std::function<void()> f) {
    this->sender = sender;
    this->signal = signal;
    this->receiver = receiver;
    this->method = method;
    disconnect(sender, signal, receiver, method);

    f();
  }

  ~TemporaryDisconnect() { connect(sender, signal, receiver, method); }
};

The code above is just to give an idea of what is my goal. Do you have any suggestions?

SGaist

Hi,

I think QSignalBlocker would be simpler.

enne9

So it can be solved just by using:

{
  const QSignalBlocker blocker(sender);
  const QSignalBlocker blocker(sender2);
  doSomething();
}

Is that right? Thank you for the quick answer.

SGaist

That's the idea yes.

enne9

But what if I want to disable a specific signal?

SGaist

If you need that fine grained surgery then it might mean that your architecture may not be optimal.

Can you give a practical use case example ?

enne9

Yeah, you are right, I found out that disabling all of them should not be a problem.
Thanks