refactor(operation,link): port __toString to Display

Move __toString ports to std::fmt::Display: convert Link's inherent
to_string() and make OperationInterface require Display instead of a
to_string() method, with each operation implementing Display.

Also fix the operation __toString output to use show(false), matching
SolverOperation::__toString() (was show(true)).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/crates/shirabe/src/package/link.rs b/crates/shirabe/src/package/link.rs
index 946c664..0157989 100644
--- a/crates/shirabe/src/package/link.rs
+++ b/crates/shirabe/src/package/link.rs
@@ -76,23 +76,26 @@ impl Link {
         &self.pretty_constraint
     }
 
-    pub fn to_string(&self) -> String {
+    pub fn get_pretty_string(&self, source_package: PackageInterfaceHandle) -> String {
         format!(
-            "{} {} {} ({})",
-            self.source,
+            "{} {} {} {}",
+            source_package.get_pretty_string(),
             self.description,
             self.target,
-            self.constraint.to_string(),
+            self.constraint.get_pretty_string()
         )
     }
+}
 
-    pub fn get_pretty_string(&self, source_package: PackageInterfaceHandle) -> String {
-        format!(
-            "{} {} {} {}",
-            source_package.get_pretty_string(),
+impl std::fmt::Display for Link {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "{} {} {} ({})",
+            self.source,
             self.description,
             self.target,
-            self.constraint.get_pretty_string()
+            self.constraint.to_string(),
         )
     }
 }