Can QtConcurrent::run be used with smart pointers to objects?

Question

Qt Documentation states that QtConcurrent::run can be used to run a member function in another thread by passing the pointer to the object as the first argument. However, I couldn't find any info if smart pointers can be used in this case. Specifically, I wanted to use it with std::shared_ptr.

Answer 1

It should be impossible to pass a smart pointer to QtConcurrent::run since there is no matching overload available.

I would suggest a solution using lambdas:

std::shared_ptr<Obj> obj_ptr(new Obj());
QtConcurrent::run([obj_ptr](){ obj_ptr->func(); });

Due to the internal reference counter of shared_ptr you don't have to worry about the life time of the object owned by the smart pointer since you capture a copy in the lambda function.

Another solution would be to pass the raw pointer:

std::shared_ptr<Obj> obj_ptr(new Obj());
QtConcurrent::run(obj_ptr.get(), &Obj::func);

But this is quite risky since you have to worry about the life time of your object.

In the end, I would prefer the first method since it is much safer.