consider changing master ffi `Association` from class type to native struct about dnp3 HOT 2 CLOSED

I don't think I agree with this. Here are my points:

• The Dispose (C#) / close (Java) pattern seems to model really well what we intend here. Similar to a file, if you just let it be collected by the garbage collector, we will close the connection. You should always close it manually when you really want to close it (like a file).
• Same thing in C. It makes sense to gracefully shutdown by explicitly destroying the association. Destroying a pointer makes sense here. The lifetime of the pointer represents the lifetime of the association.
• The destruction mechanism of this solution seems odd to me. We would pass a struct to the master saying "destroy this" but the struct would simply be copied?
• Making it a struct means users will be able to pass in whatever association handle they like.

from dnp3.

I see your point regarding it not being an opaque type anymore. I just wish that there were something like in Rust where you can have a Copyable type, but keep the inner parts private.

from dnp3.