Manage images with unique_ptr

[tobiolo]

ThreadPool cannot deal with unique_ptr in a straight-forward way, so leave it out for now.

[aardappel]

Wait, can you please explain? I doubt there is any problem with unique_ptr and threads, there is likely a different issue.

[tobiolo]

The problem is it seems is that I cannot pass the unique pointer reference into the lambda function of pool.enqueue. The compiler gives me some errors about std::invoke, ::type mismatch etc.

[tobiolo]

Sorry, I could have waited.

[aardappel]

Ok, but those errors can probably be solved. I am not sure why that would warrant removing all the multi-threading stuff, which presumably was useful.

In general, you use unique_ptr to represent the pointer that OWNS the object, not necessarily for passing pointers. It is fine to pass as T * as long as you're sure that the unique_ptr outlives it.

[tobiolo]

You are perfectly fine. This is why I would like to reintroduce ThreadPool with the other PR. I now found a way to do it and your hint was the one I needed. 🙏