No description
0ec214423e
This took me some time to figure out so it's useful to document in the
commit message.
When chaining messages from actors, the result type of a message (i.e.
the actual `<M as Message>::Result`) is sometimes itself a
`Result<T, E>`.
In many cases this leads to a situation where the return type of a
message sending process is something like (simplified):
Future<Item=Result<Foo, ConverseError>, Error=actix::MailboxError>
Due to the implementation of
`From<actix::MailboxError> for ConverseError` it is possible to use
`.from_err()` on these futures to convert the future's `Error` to
`ConverseError`.
The type `Result` apparently implements `IntoFuture`, which means that
due to some trait magic that's been applied somewhere in the futures
API a call to `flatten()` can "lift" the contained error if the error
types match and give us a "simple"
Future<Item=Foo, Error=ConverseError>
From that point on chaining becomes easy.
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| todo.org | ||