Benjamin Mahler created MESOS-3226:
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Summary: Introduce an Either type.
Key: MESOS-3226
URL: https://issues.apache.org/jira/browse/MESOS-3226
Project: Mesos
Issue Type: Improvement
Components: stout
Reporter: Benjamin Mahler
We currently don't have an abstraction in stout to capture the notion of having
a container with many types and a single value. For example, in our
abstractions like Try, rather than being able to say {{Either<Error, Value> t}}
we must encode two Options ({{Option<Error>}}, {{Option<T>}}) with the implicit
invariant that exactly one will be set.
This also comes in handy in many other places in the code. Note that we have
the ability to (1) use C++11 unions now, as well as (2) use boost's variant
directly instead of introducing Either. However, creating a named union every
time this is needed is verbose, and unions require that we externally track
which member is set. For variant, we already use this (e.g. json.hpp), but we
can benefit from the better naming as Either.
Many languages expose Either as having only two values, left and right. I'd
propose making this two or more, as is the case with variant.
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