Context manager for activating context?

[annettejanewilson]

Hi! I'm trying to make sense of the baggage and tracing APIs. I see that there is the trace.use_span context manager for taking the implicit context and replacing it with one with a new span. But I can't see anything similar for contexts in general or baggage in particular. I note that the opentelemetry specification says:

Users writing instrumentation in languages that use Context implicitly are discouraged from using the Context API directory. In those cases, users will manipulate Context through cross-cutting concerns APIs instead, in order to perform operations such as setting trace or baggage entries for a specified Context.

As far as I can tell the Python library is half-way between, is that right? For spans I can use context implicitly, but if I want to use baggage I seem to need to deal with contexts explicitly. For example to set baggage I can call baggage.set_baggage and if I specify no context it will read the implicit context, but then I still need to explicitly attach the returned context, store a token and use it to detach the context later. Would it make sense for there to be something to do this for baggage in a convenient context manager? Or perhaps I have misunderstood something?

[lzchen]

Might revisit: #732

[aabmass]

I'm in favor of a adding use_context() and/or use_baggage() convenience contextmanagers