README

It's a template to write rust derive macro.

The trait is designed for named struct. - If the field of struct has attribute #[exclude], this.field remain the same. - ElIf the field of struct is not Option: this.field = that.field.clone() - ElIf the field of struct has attribute #[force]: this.field = that.field.clone() - ElIf the field of struct is Option and doesn't have attribute #[force]: - If that.field.is_some(): this.field = that.field.clone() - If that.field.is_none(): this.field remain the same.

```rust pub trait MergeProto { fn merge_proto(&mut self, another: &Self); }

[derive(MergeProto)]

struct TestStruct { a: Option, b: Option, c: Option, #[force] d: Option, #[exclude] e: Option } let mut this = TestStruct { a: Some(1), b: None, c: Some(1), d: Some(1), e: None }; let that = TestStruct { a: Some(2), b: Some("hello".to_string()), c: None, d: None, e: Some(1) };

this.mergeproto(&that); asserteq!(this.a, Some(2)); asserteq!(this.b, Some("hello".tostring())); asserteq!(this.c, Some(1)); asserteq!(this.d, None); assert_eq!(this.e, None); ```