From 7b7b755f477c71fd4fd4f7e6f3049216b8ebc5eb Mon Sep 17 00:00:00 2001
From: Joe Doyle <joseph.doyle@trailofbits.com>
Date: Tue, 25 Nov 2025 17:04:13 -0500
Subject: [PATCH] Convert get_mark() to MARK associated constant
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Changes:
- Updated trait definition to use const MARK
- Modified derive macro to generate constants instead of methods
- Updated documentation to reflect the new API
- Adapted test to use constant reference for custom marks

Resolves #6

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>
---
 inscribe-derive/src/lib.rs | 14 +++++---------
 src/inscribe.rs            |  6 +++---
 tests/inscribe_tests.rs    |  8 +-------
 3 files changed, 9 insertions(+), 19 deletions(-)

diff --git a/inscribe-derive/src/lib.rs b/inscribe-derive/src/lib.rs
index b499ccb..2314cda 100644
--- a/inscribe-derive/src/lib.rs
+++ b/inscribe-derive/src/lib.rs
@@ -175,7 +175,7 @@ fn implement_get_inscription(dstruct: &DataStruct) -> TokenStream {
             use decree::decree::FSInput;
 
             let mut serial_out: Vec<u8> = Vec::new();
-            let mut hasher = TupleHash::v256(self.get_mark().as_bytes());
+            let mut hasher = TupleHash::v256(Self::MARK.as_bytes());
 
             // Add the struct members into the TupleHash
             #center
@@ -196,12 +196,10 @@ fn implement_default_mark(ast: &DeriveInput) -> TokenStream {
     let ident = &ast.ident;
     let ident_str = ident.to_string();
 
-    let get_mark = quote!{
-            fn get_mark(&self) -> &'static str {
-                return #ident_str;
-            }
+    let mark = quote!{
+            const MARK: &'static str = #ident_str;
         };
-    get_mark
+    mark
 }
 
 fn implement_get_addl(ast: &DeriveInput) -> TokenStream {
@@ -255,9 +253,7 @@ fn implement_get_mark(ast: &DeriveInput) -> TokenStream {
         if let Some(meta) = nested.iter().next() {
             match meta {
                 Meta::Path(path) => { mark_implementation = quote!{
-                    fn get_mark(&self) -> &'static str {
-                        self.#path()
-                    }
+                    const MARK: &'static str = #path;
                  }},
                 _ => { panic!("Invalid metadata for field attribute"); },
             }
diff --git a/src/inscribe.rs b/src/inscribe.rs
index cf9728d..858a0cb 100644
--- a/src/inscribe.rs
+++ b/src/inscribe.rs
@@ -8,14 +8,14 @@ pub type InscribeBuffer = [u8; INSCRIBE_LENGTH];
 /// contextual data into Fiat-Shamir transcripts. There are two main methods that the trait
 /// requires:
 ///
-/// `fn get_mark(&self) -> &'static str`
+/// `const MARK: &'static str`
 ///
 /// and
 ///
 /// `fn get_inscription(&self) -> FSInput`
 ///
 /// For derived structs, the `get_inscription` method will do the following:
-///     - Initialize a TupleHash with the results of `get_mark`
+///     - Initialize a TupleHash with the contents of `MARK`
 ///     - For each member of the struct, do one of three things:
 ///         + For `Inscribe` implementers, call `get_inscription` and add the results to the
 ///             TupleHash
@@ -124,7 +124,7 @@ pub type InscribeBuffer = [u8; INSCRIBE_LENGTH];
 /// ```
 ///
 pub trait Inscribe {
-    fn get_mark(&self) -> &'static str;
+    const MARK: &'static str;
     fn get_inscription(&self) -> DecreeResult<FSInput>;
     fn get_additional(&self) -> DecreeResult<FSInput> {
         let x: Vec<u8> = Vec::new();
diff --git a/tests/inscribe_tests.rs b/tests/inscribe_tests.rs
index cc75bb9..33395e2 100644
--- a/tests/inscribe_tests.rs
+++ b/tests/inscribe_tests.rs
@@ -12,7 +12,7 @@ mod tests {
     const MARK_TEST_DATA: &str = "Atypical mark!";
 
     #[derive(Inscribe)]
-    #[inscribe_mark(atypical_mark)]
+    #[inscribe_mark(MARK_TEST_DATA)]
     struct Point {
         #[inscribe(serialize)]
         #[inscribe_name(input_2)]
@@ -22,12 +22,6 @@ mod tests {
         y: i32,
     }
 
-    impl Point {
-        fn atypical_mark(&self) -> &'static str {
-            MARK_TEST_DATA
-        }
-    }
-
     #[derive(Inscribe)]
     #[inscribe_addl(additional_data_method)]
     struct InscribeTest {