could be improved.
TODO: actually specify the intended API
Handling connection errors systematically has been a cause of concern for clients of FIDL v1 because method result callbacks and connection error callbacks are implemented by different parts of the client program.
It would be desirable to consider an API which allows for localized handling of connection errors at the point of method calls (in addition to protocol level connection error handling as before).
See https://fuchsia-review.googlesource.com/#/c/23457/ for one example of how a client would otherwise work around the API deficiency.
One approach towards a better API may be constructed by taking advantage of the fact that std::function<> based callbacks are always destroyed even if they are not invoked (such as when a connection error occurs). It is possible to implement a callback wrapper which distinguishes these cases and allows clients to handle them more systematically. Unfortunately such an approach may not be able to readily distinguish between a connection error vs. proxy destruction.
Alternately we could wire in support for multiple forms of callbacks or for multiple callbacks.
Or we could change the API entirely in favor of a more explicit Promise-style mechanism.
There are lots of options here...
TBD (please feel free to amend / expand on this)
