Use cxx::function were it is appropriate

[MatthiasKillat]

Brief feature description

We have some std::function usages left in iceoryx hoofs. They should be replaced with cxx::function.
This affects constructs needing callbacks, like GenericRAII (a better name would be RAIIGuard or similar) and others.
Furthermore constructs that are not used like ActiveObject are also affected.

Note that there are no direct occurrences in posh (but indirectly, via hoofs).

Detailed information

We can replace them with cxx::function but need to choose its capacity carefully, likely on a case by case basis. We may have something global like cxx::function<Signature, 100> as well, in memory of its deceased cousin string<100> .

It could make sense to have some default (not 100 though, we should use powers of 2). Still a specific case can be used on a case by case basis also (we will learn what works best by trying it for some cases). For internal use, i.e. no user defined callbacks, this makes sense sinc ewe can just increase the capacity if needed later (it will not compile in this case).

User defined callbacks are a a different matter, but we need a bound here as well.

This issue may be broken down further to handle specific occurrences of std::function should it prove more complex.

Tasks

• Replace or remove std::function in iceoryx_hoofs
• Replace MethodCallback with cxx::function
• Remove MethodCallback from iceoryx_hoofs

[elBoberido]

@mossmaurice do you think the MethodCallback can also be replaced in the context of this issue?

[mossmaurice]

do you think the MethodCallback can also be replaced in the context of this issue?

@elBoberido That's a good idea. I would defintely do it in separate PRs. However, I think this will be quite some effort. But removing MethodCallback sooner than later would be great.

[elBoberido]

@mossmaurice shall I extend the issue name ("Use cxx::function were it is appropriate") and add two tasks, one for std::function and one for MethodCallback?

[elfenpiff]

@MatthiasKillat @mossmaurice @elBoberido

I added a subtask to also remove the MethodCallback. This was only a quick solution to capture this in a callback and with cxx::function this abstraction is not needed anymore.