Add Shl between instance and patch

struct-patch-derive/src/lib.rs

@@ -100,6 +100,27 @@ impl Patch {
         #[cfg(not(feature = "status"))]
         let patch_status_impl = quote!();
 
+        let add_impl = quote! {
+            impl core::ops::Add<#name #generics> for #struct_name #generics #where_clause {
+                type Output = #struct_name;
+
+                fn add(mut self, rhs: #name #generics) -> Self {
+                    self.apply(rhs);
+                    self
+                }
+            }
+
+            impl core::ops::Add<#struct_name #generics> for #name #generics #where_clause {
+                type Output = #struct_name;
+
+                fn add(mut self, rhs: #struct_name #generics) -> #struct_name  #where_clause {
+                    let mut rhs = rhs;
+                    rhs.apply(self);
+                    rhs
+                }
+            }
+        };
+
         let patch_impl = quote! {
             impl #generics struct_patch::traits::Patch< #name #generics > for #struct_name #generics #where_clause  {
                 fn apply(&mut self, patch: #name #generics) {
@@ -163,6 +184,8 @@ impl Patch {
             #patch_status_impl
 
             #patch_impl
+
+            #add_impl
         })
     }
 

struct-patch/examples/instance.rs

@@ -3,7 +3,7 @@ use struct_patch::Patch;
 #[derive(Default, Patch)]
 #[patch(attribute(derive(Debug, Default)))]
 struct Item {
-    field_bool: bool,
+    field_complete: bool,
     field_int: usize,
     field_string: String,
 }
@@ -12,7 +12,7 @@ struct Item {
 //
 // #[derive(Debug, Default)] // pass by patch(attribute(...))
 // struct ItemPatch {
-//     field_bool: Option<bool>,
+//     field_complete: Option<bool>,
 //     field_int: Option<usize>,
 //     field_string: Option<String>,
 // }
@@ -26,12 +26,35 @@ fn main() {
 
     assert_eq!(
         format!("{patch:?}"),
-        "ItemPatch { field_bool: None, field_int: Some(7), field_string: None }"
+        "ItemPatch { field_complete: None, field_int: Some(7), field_string: None }"
     );
 
     item.apply(patch);
 
-    assert_eq!(item.field_bool, false);
+    assert_eq!(item.field_complete, false);
     assert_eq!(item.field_int, 7);
     assert_eq!(item.field_string, "");
+
+    let another_patch = ItemPatch {
+        field_complete: None,
+        field_int: None,
+        field_string: Some("from another patch".into()),
+    };
+    let new_item = item + another_patch;
+
+    assert_eq!(new_item.field_complete, false);
+    assert_eq!(new_item.field_int, 7);
+    assert_eq!(new_item.field_string, "from another patch");
+
+    let the_other_patch = ItemPatch {
+        field_complete: Some(true),
+        field_int: None,
+        field_string: None,
+    };
+    let final_item = the_other_patch + new_item;
+    assert_eq!(final_item.field_complete, true);
+    assert_eq!(final_item.field_int, 7);
+    assert_eq!(final_item.field_string, "from another patch");
+
+    println!("instance example run passed")
 }

struct-patch/examples/patch-attr.rs

@@ -1,5 +1,5 @@
-use struct_patch::Patch;
 use serde_with::skip_serializing_none;
+use struct_patch::Patch;
 
 #[derive(Default, Patch)]
 #[patch(attribute(derive(serde::Serialize, Debug, Default)))]