Move Add to add feature

.github/workflows/test.yml

@@ -24,6 +24,7 @@ jobs:
           nix develop -c cargo run --no-default-features --example json
           nix develop -c cargo run --no-default-features --example rename-patch-struct
           nix develop -c cargo run --no-default-features --example patch-attr
+          nix develop -c cargo run --features=add --example add
           nix develop -c cargo test --no-default-features
 
       - name: Test with default features

README.md

@@ -73,6 +73,10 @@ The [examples][examples] demo following scenarios.
 - check a patch is empty or not
 - add attribute to patch struct
 
+## Features
+- status (default): provide `is_empty` method
+- add (optional): provide `+` operator between instance and patch
+
 
 [crates-badge]: https://img.shields.io/crates/v/struct-patch.svg
 [crate-url]: https://crates.io/crates/struct-patch

struct-patch-derive/Cargo.toml

@@ -20,6 +20,7 @@ syn = { version =  "2.0", features = ["parsing"] }
 
 [features]
 status = []
+add = []
 
 [dev-dependencies]
 pretty_assertions_sorted = "1.2.3"

struct-patch-derive/src/lib.rs

@@ -100,9 +100,10 @@ impl Patch {
         #[cfg(not(feature = "status"))]
         let patch_status_impl = quote!();
 
+        #[cfg(feature = "add")]
         let add_impl = quote! {
             impl core::ops::Add<#name #generics> for #struct_name #generics #where_clause {
-                type Output = #struct_name;
+                type Output = Self;
 
                 fn add(mut self, rhs: #name #generics) -> Self {
                     self.apply(rhs);
@@ -120,6 +121,8 @@ impl Patch {
                 }
             }
         };
+        #[cfg(not(feature = "add"))]
+        let add_impl = quote!();
 
         let patch_impl = quote! {
             impl #generics struct_patch::traits::Patch< #name #generics > for #struct_name #generics #where_clause  {

struct-patch/Cargo.toml

@@ -23,4 +23,7 @@ default = ["status"]
 status = [
     "struct-patch-derive/status"
 ]
+add = [
+    "struct-patch-derive/add"
+]
 

struct-patch/examples/instance.rs

@@ -3,7 +3,7 @@ use struct_patch::Patch;
 #[derive(Default, Patch)]
 #[patch(attribute(derive(Debug, Default)))]
 struct Item {
-    field_complete: bool,
+    field_bool: bool,
     field_int: usize,
     field_string: String,
 }
@@ -12,7 +12,7 @@ struct Item {
 //
 // #[derive(Debug, Default)] // pass by patch(attribute(...))
 // struct ItemPatch {
-//     field_complete: Option<bool>,
+//     field_bool: Option<bool>,
 //     field_int: Option<usize>,
 //     field_string: Option<String>,
 // }
@@ -26,35 +26,12 @@ fn main() {
 
     assert_eq!(
         format!("{patch:?}"),
-        "ItemPatch { field_complete: None, field_int: Some(7), field_string: None }"
+        "ItemPatch { field_bool: None, field_int: Some(7), field_string: None }"
     );
 
     item.apply(patch);
 
-    assert_eq!(item.field_complete, false);
+    assert_eq!(item.field_bool, 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")
 }