Use traits to keep event methods dry

book/10-protected-events.md

@@ -48,7 +48,7 @@ pub mod protected;
 //! challenge followed by a pubkey comparison) needs a live, authenticated
 //! connection and is handled in the relay layer.
 
-use crate::events::{Event, HashedEvent};
+use crate::events::HasTags;
 use crate::tags::Tags;
 ```
 
@@ -91,23 +91,25 @@ impl Tag {
 ## Methods on event types
 
 A caller holding an event wants to ask whether it is protected without
-reaching for its tags directly. Both `HashedEvent` and `Event` carry a
-`Tags` field, so the method facades delegate to the free function.
+reaching for its tags directly. Following the pattern from expiration, the
+query is an extension trait bounded on [`HasTags`], so one default method
+serves every event type. With `coracle_lib::prelude::*` in scope,
+`event.is_protected()` works on both `HashedEvent` and `Event`.
 
 ```rust {file=coracle-lib/src/protected.rs}
-impl HashedEvent {
+/// Protected-event queries on any event that carries tags.
+pub trait EventExtensionProtected: HasTags {
     /// Whether this event carries the NIP-70 protected marker.
-    pub fn is_protected(&self) -> bool {
-        is_protected(&self.tags)
+    fn is_protected(&self) -> bool {
+        is_protected(self.tags())
     }
 }
 
-impl Event {
-    /// Whether this event carries the NIP-70 protected marker.
-    pub fn is_protected(&self) -> bool {
-        is_protected(&self.tags)
-    }
-}
+impl<T: HasTags> EventExtensionProtected for T {}
+```
+
+```rust {file=coracle-lib/src/prelude.rs}
+pub use crate::protected::EventExtensionProtected;
 ```
 
 ## Usage patterns