Merge 8aa8b492ea into dd0634c483

errors6: Add alternative solution using From trait

exercises/22_clippy/clippy3.rs

@@ -4,9 +4,11 @@
 #[rustfmt::skip]
 #[allow(unused_variables, unused_assignments)]
 fn main() {
-    let my_option: Option<()> = None;
+    let my_option: Option<&str> = None;
+    // Assume that you don't know the value of `my_option`.
+    // In the case of `Some`, we want to print its value.
     if my_option.is_none() {
-        println!("{:?}", my_option.unwrap());
+        println!("{}", my_option.unwrap());
     }
 
     let my_arr = &[

solutions/13_error_handling/errors6.rs

@@ -29,6 +29,21 @@ impl ParsePosNonzeroError {
     }
 }
 
+// As an alternative solution, implementing the `From` trait allows for the
+// automatic conversion from a `ParseIntError` into a `ParsePosNonzeroError`
+// using the `?` operator, without the need to call `map_err`.
+//
+// ```
+// let x: i64 = s.parse()?;
+// ```
+//
+// Traits like `From` will be dealt with in later exercises.
+impl From<ParseIntError> for ParsePosNonzeroError {
+    fn from(err: ParseIntError) -> Self {
+        ParsePosNonzeroError::ParseInt(err)
+    }
+}
+
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 

solutions/22_clippy/clippy3.rs

@@ -3,11 +3,11 @@ use std::mem;
 #[rustfmt::skip]
 #[allow(unused_variables, unused_assignments)]
 fn main() {
-    let my_option: Option<()> = None;
+    let my_option: Option<&str> = None;
     // `unwrap` of an `Option` after checking if it is `None` will panic.
     // Use `if-let` instead.
     if let Some(value) = my_option {
-        println!("{value:?}");
+        println!("{value}");
     }
 
     // A comma was missing.