[BUG] Arguments are passed by value

[ThibaultDECO]

It would be useful to specify in the documentation that, when submitting tasks, arguments are passed by value by default (see std::bind()), which can significantly slow down the pool.

And that one should use std::ref() to pass arguments by reference, such as:
auto my_future = pool.submit(task, arg1, std::ref(arg2));

It would be convenient if there was a way for arguments to be passed by reference automatically when the function definition specifies it, but not sure how to do it.

[bshoshany]

Thanks for the suggestion! I will incorporate this in the documentation in the next release.

Unfortunately, as far as I know, it's impossible to define submit() or push_task() so that they can accept references automatically. This is because std::function needs the std::ref (or std::cref for constant references) wrappers to be used explicitly in the constructor in order to take arguments that are references. (But if you find a way to bypass that, please let me know!)

[bshoshany]

Update: v3.5.0, which was just released, includes instructions for passing arguments by reference in README.md.