traits3 solution

exercises/15_traits/traits3.rs

@@ -1,9 +1,8 @@
-// Your task is to implement the Licensed trait for both structures and have
-// them return the same information without writing the same function twice.
-//
-// Consider what you can add to the Licensed trait.
-
 trait Licensed {
+    // TODO: Add a default implementation for `licensing_info` so that
+    // implementors like the two structs below can share that default behavior
+    // without repeating the function.
+    // The default license information should be the string "Default license".
     fn licensing_info(&self) -> String;
 }
 
@@ -15,8 +14,8 @@ struct OtherSoftware {
     version_number: String,
 }
 
-impl Licensed for SomeSoftware {} // Don't edit this line
+impl Licensed for SomeSoftware {} // Don't edit this line.
-impl Licensed for OtherSoftware {} // Don't edit this line
+impl Licensed for OtherSoftware {} // Don't edit this line.
 
 fn main() {
     // You can optionally experiment here.
@@ -28,7 +27,7 @@ mod tests {
 
     #[test]
     fn is_licensing_info_the_same() {
-        let licensing_info = String::from("Some information");
+        let licensing_info = "Default license";
         let some_software = SomeSoftware { version_number: 1 };
         let other_software = OtherSoftware {
             version_number: "v2.0.0".to_string(),

rustlings-macros/info.toml

@@ -772,11 +772,12 @@ the value is owned anyway."""
 name = "traits3"
 dir = "15_traits"
 hint = """
-Traits can have a default implementation for functions. Structs that implement
+Traits can have a default implementation for functions. Data types that
-the trait can then use the default version of these functions if they choose not
+implement the trait can then use the default version of these functions
-to implement the function themselves.
+if they choose not to implement the function themselves.
 
-See the documentation at: https://doc.rust-lang.org/book/ch10-02-traits.html#default-implementations"""
+Related section in The Book:
+https://doc.rust-lang.org/book/ch10-02-traits.html#default-implementations"""
 
 [[exercises]]
 name = "traits4"

solutions/15_traits/traits3.rs

@@ -1 +1,36 @@
-// Solutions will be available before the stable release. Thank you for testing the beta version 🥰
+trait Licensed {
+    fn licensing_info(&self) -> String {
+        "Default license".to_string()
+    }
+}
+
+struct SomeSoftware {
+    version_number: i32,
+}
+
+struct OtherSoftware {
+    version_number: String,
+}
+
+impl Licensed for SomeSoftware {}
+impl Licensed for OtherSoftware {}
+
+fn main() {
+    // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn is_licensing_info_the_same() {
+        let licensing_info = "Default license";
+        let some_software = SomeSoftware { version_number: 1 };
+        let other_software = OtherSoftware {
+            version_number: "v2.0.0".to_string(),
+        };
+        assert_eq!(some_software.licensing_info(), licensing_info);
+        assert_eq!(other_software.licensing_info(), licensing_info);
+    }
+}