[Discussion] It's not necessary to use GAT in the Registry trait‘s definition

[onewe]

Hi guys, I have been writting Nacos Registry module recently, I found that It's not necessary to use GAT in the Registry trait‘s definition, for the listener must be shareable and can't be removed ownership. so I think use Arc<dyn NotifyListener> is better.

我最近在写 nacos registry 模块, 我发现在 registry 定义中完全没必要使用 GAT, 因为 listener 肯定是一个共享的且不能被消费掉所有权的. 所以我觉得使用 Arc<dyn NotifyListener> 会更好点.

now

pub trait Registry {
    type NotifyListener;

    fn register(&mut self, url: Url) -> Result<(), crate::StdError>;
    fn unregister(&mut self, url: Url) -> Result<(), crate::StdError>;

    fn subscribe(&self, url: Url, listener: Self::NotifyListener) -> Result<(), crate::StdError>;
    fn unsubscribe(&self, url: Url, listener: Self::NotifyListener) -> Result<(), crate::StdError>;
}

change

pub type NotifyListener = Arc<dyn NotifyListener + Send + Sync + 'static>;
pub trait Registry {
    fn register(&mut self, url: Url) -> Result<(), crate::StdError>;
    fn unregister(&mut self, url: Url) -> Result<(), crate::StdError>;

    fn subscribe(&self, url: Url, listener: NotifyListener) -> Result<(), crate::StdError>;
    fn unsubscribe(&self, url: Url, listener: NotifyListener) -> Result<(), crate::StdError>;
}