errors exercise: improve instructions, add a challenge

exercise/errors/src/lib.rs

@@ -1,18 +1,18 @@
 // 1. Create a DolphinError type representing the following three conditions:
-// - Hungry - An dolphin is hungry
-// - TooYoung - An dolphin is too young
+// - Hungry - The dolphin is hungry
+// - TooYoung - The dolphin is too young
 // - LongName - The dolphin's name is too long and annoying to say
 //
 // As a reminder, here are the 5 Guidelines for creating an error type:
 // (1) Use an `enum` for your error type
 // (2) Your error conditions should be enum variants grouped in as few enums as makes sense
-// (3) Don't expose error types other than your own (you don't have to do anything for this one)
+// (3) Don't expose error types other than your own (not going to be a problem for this exercise)
 // (4) Make your enum non-exhaustive
 // (5) Implement the Debug, Display, and Error traits
-// (5b) You can use thiserror's `Error` macro to derive Display and Error.h
+// (5b) You can use thiserror's `Error` macro to derive the Display and Error traits
 //
-// Once you have completed the error type correctly, you should be able to run `cargo build --lib`
-// without any errors.
+// Once you have completed defining the error type correctly, you should be able to run
+// `cargo build --lib` without any build errors or warnings. Then go to main.rs and continue with #2
 
 // pub enum DolphinError...
 

exercise/errors/src/main.rs

@@ -3,6 +3,7 @@
 use aquarium::Dolphin;
 
 // (You already did #1 in lib.rs, right?)
+//
 // 2a. Uncomment and finish the play_time function below
 // - Bring anyhow::Result into scope with a `use` statement
 // - Have the play_time function return a `Result<Vec<String>>`. The vector of Strings will
@@ -10,18 +11,16 @@ use aquarium::Dolphin;
 
 // fn play_time(dolphin: &Dolphin) -> ... {
 //     let mut responses = vec![];
-//     // 2b. There are three methods on the Dolphin struct:
-//     // - .say_your_name()
-//     // - .flip()
-//     // - .shake_hands()
+//     // 2b. Call the .say_your_name() method on `dolphin`, use `?` to unwrap the value, and push
+//     // the value onto the `responses` vector.
 //     //
-//     // For each of the three methods above:
-//     // - Call the method on `dolphin`, using the `?` operator to unwrap the value / return the error
-//     // - Push the unwrapped string onto the `responses` vector using the .push() method
-
 //     // let response = ...    // this can be done with an intermediate variable...
 //     // responses.push( ... ) // ...or all on one line. Either way is fine!
-
+//     //
+//     // 2c. Do the same thing as #2b for the .flip() method
+//     //
+//     // 2d. Do the same thing as #2b for the .shake_hands() method
+//
 //     Ok(responses)
 // }
 
@@ -49,6 +48,9 @@ fn main() {
         },
     ];
     for dolphin in &dolphins {
+        // Challenge: Change main() so that it returns a Result, and instead of handling the error
+        // that play_time returns, use the try operator to only handle the success condition. How
+        // does the output of the program change?
         match play_time(dolphin) {
             Ok(responses) => {
                 println!("{} did a FABULOUS PERFORMANCE!", dolphin.name);