Trait MessageName 

pub trait MessageName {
    const PACKAGE: &'static str;
    const NAME: &'static str;
    const FULL_NAME: &'static str;
    const TYPE_URL: &'static str;
}

Compile-time access to a generated message’s protobuf identifiers.

Generic code that needs to name a message type — type-erased event registries, structured logging, Any packing, schema lookups — can bound on T: MessageName and read PACKAGE, NAME, FULL_NAME, or TYPE_URL without descriptor machinery or runtime reflection. All four are &'static str literals computed at codegen time, so there’s no allocation or concatenation at runtime — unlike prost::Name, whose full_name() and type_url() are runtime format! calls.

Bring buffa::MessageName into scope to use MyMessage::FULL_NAME. Without the trait in scope, use <MyMessage as buffa::MessageName>::FULL_NAME.

Codegen implements MessageName for both the owned message type and its zero-copy view type (MyMessageView<'a>), so the same generic bound dispatches either. The trait has no Message supertrait — it doesn’t reach into the wire codec and a name-keyed registry should be able to register a type without proving it can encode.

Hand-written Message implementations can opt in by also implementing MessageName; it is a separate trait specifically so that omitting it stays non-breaking. For messages that also implement ExtensionSet, FULL_NAME is guaranteed equal to ExtensionSet::PROTO_FQN; the inherent MyMessage::TYPE_URL const is equal to TYPE_URL. All derive from the same proto_fqn source in codegen.

Because the only items are associated consts, this trait is not object-safe (dyn MessageName does not compile). Use it as a generic bound (fn foo<T: MessageName>()), not a trait object.

/// A name-keyed registry can register any `MessageName` type — owned
/// or view — without proving it can encode.
fn registry_key<T: MessageName>() -> &'static str {
    T::FULL_NAME
}
assert_eq!(registry_key::<Demo>(), "demo.Demo");

Required Associated Constants

const PACKAGE: &'static str

The protobuf package the message is declared in.

"my.pkg" for package my.pkg;. Empty string for the unnamed root package. Does not include a leading or trailing dot.

const NAME: &'static str

The unqualified message name, with . between nesting levels.

"Foo" for a top-level message; "Outer.Inner" for a message nested inside Outer. This is the “type name relative to the package” — what prost::Name::NAME calls the same thing — not DescriptorProto.name, which is only the leaf segment ("Inner") for nested types.

const FULL_NAME: &'static str

The fully-qualified protobuf type name with no leading dot.

"my.pkg.Outer.Inner" for a nested message in package my.pkg, or just "Foo" for a top-level message in the unnamed root package. Equal to PACKAGE + "." + NAME (with the joining dot omitted when PACKAGE is empty); shipped as its own const because consumers almost always want the joined form and the dotted string can’t be re-split unambiguously (foo.Bar.Baz could be package foo.Bar + message Baz, or package foo + nested Bar.Baz).

const TYPE_URL: &'static str

The google.protobuf.Any.type_url form for this message.

"type.googleapis.com/" + FULL_NAME. This is the value the runtime stores in Any::type_url when packing a message, and the one a generic Any registry should key on.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors