Added first rust-fix: derive display trait

Author: marvin-hansen

derive-display/Cargo.toml

@@ -0,0 +1,9 @@
+[package]
+name = "derive-display"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+parse-display = "0.6.0"

derive-display/src/derived_display.rs

@@ -0,0 +1,17 @@
+use parse_display::{Display, FromStr};
+
+#[derive(Display, FromStr, PartialEq, Debug)]
+#[display("{a}-{b}")]
+pub struct MyStruct {
+    a: u32, b: u32,
+}
+
+impl MyStruct {
+    pub fn new(a: u32, b: u32) -> MyStruct { MyStruct { a, b } }
+}
+
+#[derive(Display, FromStr, PartialEq, Debug)]
+#[display(style = "snake_case")]
+pub enum MyEnum {
+    VarA, VarB,
+}

derive-display/src/main.rs

@@ -0,0 +1,46 @@
+mod no_derive;
+mod derived_display;
+
+fn main() {
+    no_derive();
+}
+
+fn no_derive() {
+    println!("Implemented Display method");
+    assert_eq!(no_derive::MyEnum::VarA.to_string(), "VarA");
+    assert_eq!(no_derive::MyEnum::VarB.to_string(), "VarB");
+
+    let a = no_derive::MyEnum::VarA;
+    let b = no_derive::MyEnum::VarB;
+    println!("{}", a);
+    println!("{}", b);
+
+    let s = no_derive::MyStruct::new(10,20);
+    println!("{}", s);
+    println!();
+}
+
+
+fn derive() {
+    //  cargo add parse-display-derive
+    //https://crates.io/crates/parse-display-derive
+    println!("Derived Display method");
+
+    let s = derived_display::MyStruct::new(10, 20);
+    assert_eq!(s.to_string(), "10-20");
+    assert_eq!("10-20".parse(), Ok(s));
+
+
+    let s = derived_display::MyStruct::new(10, 20);
+    println!("{}", s);
+
+    assert_eq!(derived_display::MyEnum::VarA.to_string(), "var_a");
+    assert_eq!("var_a".parse(), Ok(derived_display::MyEnum::VarA));
+
+    let a = derived_display::MyEnum::VarA;
+    let b = derived_display::MyEnum::VarB;
+
+    println!("{}", a);
+    println!("{}", b);
+    println!();
+}

derive-display/src/no_derive.rs

@@ -0,0 +1,36 @@
+use std::fmt;
+
+pub enum MyEnum {
+    VarA,
+    VarB,
+}
+
+impl MyEnum {
+    pub fn as_str(&self) -> &'static str {
+        match self {
+            MyEnum::VarA => "VarA",
+            MyEnum::VarB => "VarB",
+        }
+    }
+}
+
+impl fmt::Display for MyEnum {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.as_str())
+    }
+}
+
+pub struct MyStruct {
+    a: u32,
+    b: u32,
+}
+
+impl MyStruct {
+    pub fn new(a: u32, b: u32) -> MyStruct { MyStruct { a, b } }
+}
+
+impl fmt::Display for MyStruct {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}-{}", self.a, self.b)
+    }
+}