Partial Move

When some non-Copy fields from a struct is moved, but not all.

---

The variable binding the struct instance is still valid, but the fields that is moved is invalid, thus it’s a “partial” move.

We can still use fields that are not partially moved. Trying to use fields that have been partially moved will cause a compilation error.

Fields that are Copy is implicitly copied.

Recall

Copy is a marker trait that means bitwise copy is safe. Types that are Copy are automatically copied instead of moved.

struct Template {
	cat: String,
	dog: String
}
 
impl Default for Template {
	fn default() -> Self {
		Template {
			cat: "Meow".to_string(),
			dog: "Bark".to_string()
		}
	}
}
 
fn main() {
	let template = Template::default();
	let concrete = Template {
		cat: "Nya".to_string(),
		..template  // template.dog is "partially" moved
	};
	println!("{}", template.cat);  // Valid
	println!("{}, {}", concrete.cat, concrete.dog);  // valid
    // NOTE: Invalid. template.cat is partially moved to concrete.cat
	// println!("{}", template.cat);
}