Remove default requirement (#7)

- remove `Default` requirement
- `default_patch` -> `new_empty_patch`

Cargo.toml

@@ -8,7 +8,7 @@ members = [
 
 [workspace.package]
 authors = ["Antonio Yang <[email protected]>"]
-version = "0.1.5"
+version = "0.2.0"
 edition = "2021"
 categories = ["Accessibility"]
 keywords = ["struct", "patch", "macro", "derive", "overlay"]

README.md

@@ -56,7 +56,8 @@ Following are attributes you can easy to use patch a struct as you want
 The [`struct_patch::traits::Patch`][patch-trait] will implement, you can check the docs for details.
   - `apply`: apply the patch, only update the existing fields
   - `into_patch_by_diff`: diff on a previous state and get the patch instance
-  - `default_patch`: get an empty patch instance
+  - `new_empty_patch`: get an empty patch instance
+
 
 ## Methods for patch structure
 With `status` feature, the patch struct will implement [`PatchStatus`][patch-status-trait] trait and providing following methods:

struct-patch-derive/src/lib.rs

@@ -30,7 +30,7 @@ use quote::quote;
 /// ```rust
 /// use struct_patch::traits::Patch;
 /// let mut item = Item::default();
-/// let mut patch = Item::default_patch();
+/// let mut patch = Item::new_empty_patch();
 /// assert(patch.is_empty());
 ///
 /// patch.field_int = Some(7);
@@ -132,6 +132,8 @@ pub fn derive_patch(item: TokenStream) -> TokenStream {
     #[cfg(feature = "status")]
     let field_names_clone2 = field_names.clone();
     let field_names_clone3 = field_names.clone();
+    let field_names_clone4 = field_names.clone();
+
     let wrapped_types = wrapped_fields.iter().map(|(_, t)| t);
 
     let mut output = if let Some(patch_derive) = patch_derive {
@@ -143,7 +145,6 @@ pub fn derive_patch(item: TokenStream) -> TokenStream {
         )
     } else {
         quote::quote!(
-            #[derive(Default)]
             pub struct #patch_struct_name {
                 #(pub #field_names: #wrapped_types,)*
             }
@@ -178,14 +179,22 @@ pub fn derive_patch(item: TokenStream) -> TokenStream {
             }
 
             fn into_patch_by_diff(self, previous_struct: Self) -> #patch_struct_name {
-                let mut p = Self::default_patch();
+                let mut p = Self::new_empty_patch();
                 #(
                     if self.#field_names_clone3 != previous_struct.#field_names_clone3 {
                         p.#field_names_clone3 = Some(self.#field_names_clone3);
                     }
                 )*
                 p
             }
+
+            fn new_empty_patch() -> #patch_struct_name {
+                #patch_struct_name {
+                    #(
+                        #field_names_clone4: None,
+                    )*
+                }
+            }
         }
     )
     .to_string();

struct-patch-trait/src/lib.rs

@@ -1,17 +1,15 @@
 /// Define the behavior between patch struct and original sturct
 pub mod traits {
     /// The trait can apply patch and generete corresponding patch instance
-    pub trait Patch<P: Default> {
+    pub trait Patch<P> {
         /// Apply the patch, only update the existing fields
         fn apply(&mut self, patch: P);
 
         /// Diff on a previous state and into the patch instance
         fn into_patch_by_diff(self, previous_struct: Self) -> P;
 
         /// Get an empty patch instance
-        fn default_patch() -> P {
-            P::default()
-        }
+        fn new_empty_patch() -> P;
     }
 
     #[cfg(feature = "status")]

struct-patch/Cargo.toml

@@ -12,8 +12,8 @@ readme.workspace = true
 
 
 [dependencies]
-struct-patch-trait = { version = "=0.1.5", path = "../struct-patch-trait" }
-struct-patch-derive = { version = "=0.1.5", path = "../struct-patch-derive" }
+struct-patch-trait = { version = "=0.2.0", path = "../struct-patch-trait" }
+struct-patch-derive = { version = "=0.2.0", path = "../struct-patch-derive" }
 
 [dev-dependencies]
 serde_json = "1.0"

struct-patch/examples/instance.rs

@@ -22,9 +22,7 @@ fn main() {
 
     let mut item = Item::default();
 
-    let mut patch = Item::default_patch();
-    // the same as
-    // let mut patch = ItemPatch::default();
+    let mut patch = Item::new_empty_patch();
 
     patch.field_int = Some(7);
 

struct-patch/examples/rename-patch-struct.rs

@@ -21,7 +21,7 @@ struct Item {
 fn main() {
     use struct_patch::traits::Patch;
 
-    let patch = Item::default_patch();
+    let patch = Item::new_empty_patch();
 
     assert_eq!(
         format!("{patch:?}"),

struct-patch/examples/status.rs

@@ -14,7 +14,7 @@ fn main() {
     use struct_patch::traits::Patch;
     use struct_patch::traits::PatchStatus;
 
-    let mut patch = Item::default_patch();
+    let mut patch = Item::new_empty_patch();
 
     assert!(patch.is_empty()); // provided by PatchStatus
     patch.field_int = Some(7);