feat: add hello-derive-more

examples/r3/hello-derive-more/.gitignore

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+target

examples/r3/hello-derive-more/Cargo.toml

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+[package]
+name = "hello-derive-more"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+derive_more = { version = "1.0.0", features = ["add", "display", "from", "from_str"] }

examples/r3/hello-derive-more/src/main.rs

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+use derive_more::{Add, Display, From, FromStr};
+
+#[derive(FromStr, Display)]
+pub struct PhoneNumber(String);
+
+#[derive(Clone, Copy, From, Display, Add)]
+#[display("{} years", _0)]
+pub struct Years(u32);
+
+fn main() {
+    // Use parse.
+    let num = "123-4567".parse::<PhoneNumber>().unwrap();
+    println!("1️⃣ Phone number is {}", num);
+
+    // Use from_str.
+    let num = PhoneNumber::from_str("123-4567").unwrap();
+    println!("2️⃣ Phone number is {}", num);
+
+    // Use from and Add.
+    let age_1 = Years::from(5);
+    let age_2 = Years::from(2);
+    println!("3️⃣ {} + {} = {}", age_1, age_2, age_1 + age_2);
+}