refactor: expose and use THandlerOutEvent type alias
#3368
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| @@ -297,7 +297,7 @@ pub enum PoolEvent<THandler: IntoConnectionHandler> { | |||
| id: ConnectionId, | |||
| peer_id: PeerId, | |||
| /// The produced event. | |||
| event: THandlerOutEvent<THandler>, | |||
| event: <<THandler as IntoConnectionHandler>::Handler as ConnectionHandler>::OutEvent, | |||
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I temporarily inlined this one so that I can delete the 2nd type alias named THandlerOutEvent defined in swarm::behaviour.
This will be simplified to ConnectionHandler::OutEvent in #3254.
swarm/src/behaviour.rs
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| @@ -122,7 +119,7 @@ pub(crate) type THandlerOutEvent<THandler> = | |||
| /// } | |||
| /// } | |||
| /// ``` | |||
| pub trait NetworkBehaviour: 'static { | |||
| pub trait NetworkBehaviour: Sized + 'static { | |||
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This requires a Sized bound now but I'd honestly not know why a NetworkBehaviourwouldn't be sized ...
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How is the requirement to be Sized related to this change?
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I think it is because I am now using Self within a function signature via a type-alias. To be frank, I just followed the compiler 🙃
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I would prefer to avoid casually introducing trait bounds without careful consideration. Is there any way around introducing this trait bound? Is this pull request worth doing given the added complexity.
I would have to dig deeper here. Based on intuition, adding Sized, Send or Sync unintentionally has not proven to be good ideas in the past.
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Fair point! I never looked deeply into it but apparently, requiring Sized prohibits the use as a trait object: https://doc.rust-lang.org/std/marker/trait.Sized.html
I'll try to work around it.
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Turns out it is not needed, lol 😂
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Fair point! I never looked deeply into it but apparently, requiring
Sizedprohibits the use as a trait object:I'll try to work around it.
yeah, that's why you can't have Box<dyn Clone> for example
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Thanks for investigating. Great to see it not being needed.
|
This pull request has merge conflicts. Could you please resolve them @thomaseizinger? 🙏 |
swarm/src/behaviour.rs
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| @@ -122,7 +119,7 @@ pub(crate) type THandlerOutEvent<THandler> = | |||
| /// } | |||
| /// } | |||
| /// ``` | |||
| pub trait NetworkBehaviour: 'static { | |||
| pub trait NetworkBehaviour: Sized + 'static { | |||
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I would prefer to avoid casually introducing trait bounds without careful consideration. Is there any way around introducing this trait bound? Is this pull request worth doing given the added complexity.
I would have to dig deeper here. Based on intuition, adding Sized, Send or Sync unintentionally has not proven to be good ideas in the past.
Previously, we used the full reference to the `OutEvent` of the `ConnectionHandler` in all implementations of `NetworkBehaviour`. Not only is this very verbose, it is also more brittle to changes. With the current implementation plan for libp2p#2824, we will be removing the `IntoConnectionHandler` abstraction. Using a type-alias to refer to the `OutEvent` makes the migration much easier.
Description
Previously, we used the full reference to the
OutEventof theConnectionHandlerin all implementations ofNetworkBehaviour. Not only is this very verbose, it is also more brittle to changes. With the current implementation plan for #2824, we will be removing theIntoConnectionHandlerabstraction. Using a type-alias to refer to theOutEventmakes the migration much easier.Notes
This will reduce the diff in #3254.
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Change checklist
I have added tests that prove my fix is effective or that my feature worksA changelog entry has been made in the appropriate crates