Boy, is this confusing me.
This:
use trading:T;
pub struct TService {
hold: domain::Hold,
}
#[tonic::async_trait]
impl TImpl for TService {
pub fn new() -> Self {
let h = domain::Hold::new();
Self { h }
}
...
fails to compile with:
error[E0407]: method new is not a member of trait T
I am stumped. If the interface is not implemented this syntax works. I've done lots of Googling and don't understand what I'm missing. (T is a tonic-generated gRPC server interface.)
Use a separate impl block for items that aren't in the trait
use trading:T;
pub struct TService {
hold: domain::Hold,
}
impl TService {
pub fn new() -> Self {
let h = domain::Hold::new();
Self { h }
}
}
#[tonic::async_trait]
impl TImpl for TService {
//...
}
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I'd actually tried that before and it didn't compile, but I realize now I had a typo.
It does compile.
But it never runs. That's because the TImpl instance is created by tonic.
So it seems that associated some static data with a trait impl when you don't control creation of instances is not straightforward.
I just want the gRPC service to be able to init & cache some data.
How would you go about this? I hope I was clear enough, let me know if not.
Something like this should work.
let mut server = tonic::transport::Server::builder();
let svc = T::new(TService::new());
server.add_service(svc).serve(grpc_addr).await
The fix was to replace
let service = TService::Default();
with
let service = TService::new();
in main() (where the gRPC server is instantiated and handed the service).
Where does the Default implementation come frome? It's usually best practice to make sure that Foo::default and Foo::new behave the same.
1 Like
