lifetimes let us remove trait bound

Author: molpopgen

src/traits.rs

@@ -136,7 +136,7 @@ impl private::NewTypeMarker for crate::PopulationId {}
 #[cfg_attr(doc_cfg, doc(cfg(feature = "provenance")))]
 impl private::NewTypeMarker for crate::ProvenanceId {}
 
-pub trait TableColumn<I, T: Copy>:
+pub trait TableColumn<I, T>:
     std::ops::Index<I, Output = T>
     + std::ops::Index<usize, Output = T>
     + std::ops::Index<crate::SizeType, Output = T>
@@ -146,7 +146,10 @@ pub trait TableColumn<I, T: Copy>:
     fn get(&self, at: usize) -> Option<&T>;
     fn get_with_id(&self, at: I) -> Option<&T>;
     fn get_with_size_type(&self, at: crate::SizeType) -> Option<&T>;
-    fn iter(&self) -> impl Iterator<Item = T> + '_;
+    fn iter<'a, 'b>(&'a self) -> impl Iterator<Item = &'b T>
+    where
+        'a: 'b,
+        T: 'b;
 }
 
 impl<T> private::TableColumnMarker for crate::table_column::OpaqueTableColumn<'_, T> {}
@@ -182,7 +185,11 @@ where
         self.0.get(usize::try_from(at).unwrap())
     }
 
-    fn iter(&self) -> impl Iterator<Item = T> + '_ {
-        self.0.iter().cloned()
+    fn iter<'a, 'b>(&'a self) -> impl Iterator<Item = &'b T>
+    where
+        'a: 'b,
+        T: 'b,
+    {
+        self.0.iter()
     }
 }