zoo VS function2

You could try to implement a type-erasing container, e.g. a lightweight version of zoo. The talks Breaking Dependencies: Type Erasure - A Design Analysis by Klaus Iglberger and Type Erasure exhibits Emergent Behavior by Eduardo Madrid might help.

Fixed size function wrappers are not only limited and also a waste of space. Use a configurable function wrapper like fu2 with a stack allocator and set small object optimizer capacity to 0.

std::function wasn't cutting it for me, but I ended up going with fu2::function. It comes with a lot of features (almost too many), but the header size and compile times are comparable to , and it fit my needs pretty well.

Thank you, function2 is also used heavily in Idle as a type-erasure backend for continuable that is the primary asynchronous task abstraction.

You can write your own std::function, too, nor is it the only STL type that can take a capturing lambda (std::packaged_task for example).

A capturing lambda is just a class with an operator(). It's complicated to do what std::function does, but fully possible.

In fact, custom std::function replacements have better lambda support than std::function itself. Such as unique_function in https://github.com/Naios/function2 which can handle non-copyable lambdas.