1

Author: ctrlshiftm129

exercises/enums/enums1.rs

@@ -2,11 +2,14 @@
 //
 // No hints this time! ;)
 
-// I AM NOT DONE
 
 #[derive(Debug)]
 enum Message {
     // TODO: define a few types of messages as used below
+    Quit,
+    Echo,
+    Move,
+    ChangeColor
 }
 
 fn main() {

exercises/enums/enums2.rs

@@ -3,11 +3,14 @@
 // Execute `rustlings hint enums2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 #[derive(Debug)]
 enum Message {
     // TODO: define the different variants used below
+    Move{x:i32, y:i32},
+    Echo(String),
+    ChangeColor(u8,u8,u8),
+    Quit
 }
 
 impl Message {

exercises/enums/enums3.rs

@@ -5,10 +5,12 @@
 // Execute `rustlings hint enums3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 enum Message {
-    // TODO: implement the message variant types based on their usage below
+    // TODO: define the different variants used below
+    Move(Point),
+    Echo(String),
+    ChangeColor(u8,u8,u8),
+    Quit
 }
 
 struct Point {
@@ -43,6 +45,12 @@ impl State {
         // variants
         // Remember: When passing a tuple as a function argument, you'll need
         // extra parentheses: fn function((t, u, p, l, e))
+        match message {
+            Message::Move(x) => self.move_position(x),
+            Message::ChangeColor(x, y, z) => self.change_color((x, y, z)),
+            Message::Quit => self.quit(),
+            Message::Echo(x) => self.echo(x),
+        };
     }
 }
 

exercises/error_handling/errors1.rs

@@ -9,14 +9,12 @@
 // Execute `rustlings hint errors1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
-pub fn generate_nametag_text(name: String) -> Option<String> {
+pub fn generate_nametag_text(name: String) -> Result<String, String> {
     if name.is_empty() {
         // Empty names aren't allowed.
-        None
+        Err("`name` was empty; it must be nonempty.".into())
     } else {
-        Some(format!("Hi! My name is {}", name))
+        Ok(format!("Hi! My name is {}", name))
     }
 }
 
@@ -40,4 +38,4 @@ mod tests {
             Err("`name` was empty; it must be nonempty.".into())
         );
     }
-}
+}

exercises/error_handling/errors2.rs

@@ -19,16 +19,16 @@
 // Execute `rustlings hint errors2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;
     let qty = item_quantity.parse::<i32>();
-
-    Ok(qty * cost_per_item + processing_fee)
+    match qty {
+        Ok(v) => Ok(v * cost_per_item + processing_fee),
+        Err(e) => Err(e),
+    }
 }
 
 #[cfg(test)]

exercises/error_handling/errors3.rs

@@ -7,11 +7,9 @@
 // Execute `rustlings hint errors3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::num::ParseIntError;
 
-fn main() {
+fn main() -> Result<(), ParseIntError> {
     let mut tokens = 100;
     let pretend_user_input = "8";
 
@@ -23,6 +21,7 @@ fn main() {
         tokens -= cost;
         println!("You now have {} tokens.", tokens);
     }
+    Ok(())
 }
 
 pub fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {

exercises/error_handling/errors4.rs

@@ -3,8 +3,6 @@
 // Execute `rustlings hint errors4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 #[derive(PartialEq, Debug)]
 struct PositiveNonzeroInteger(u64);
 
@@ -17,7 +15,13 @@ enum CreationError {
 impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<PositiveNonzeroInteger, CreationError> {
         // Hmm...? Why is this only returning an Ok value?
-        Ok(PositiveNonzeroInteger(value as u64))
+        if value < 0 {
+            Err(CreationError::Negative)
+        } else if value == 0 {
+            Err(CreationError::Zero)
+        } else {
+            Ok(PositiveNonzeroInteger(value as u64))
+        }
     }
 }
 
@@ -29,4 +33,4 @@ fn test_creation() {
         PositiveNonzeroInteger::new(-10)
     );
     assert_eq!(Err(CreationError::Zero), PositiveNonzeroInteger::new(0));
-}
+}

exercises/error_handling/errors5.rs

@@ -22,14 +22,13 @@
 // Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 use std::error;
+use std::error::Error;
 use std::fmt;
 use std::num::ParseIntError;
 
 // TODO: update the return type of `main()` to make this compile.
-fn main() -> Result<(), Box<dyn ???>> {
+fn main() -> Result<(), Box<dyn Error>> {
     let pretend_user_input = "42";
     let x: i64 = pretend_user_input.parse()?;
     println!("output={:?}", PositiveNonzeroInteger::new(x)?);
@@ -68,4 +67,4 @@ impl fmt::Display for CreationError {
     }
 }
 
-impl error::Error for CreationError {}
+impl error::Error for CreationError {}

exercises/error_handling/errors6.rs

@@ -1,38 +1,38 @@
-// errors6.rs
+// errors5.rs
 //
-// Using catch-all error types like `Box<dyn error::Error>` isn't recommended
-// for library code, where callers might want to make decisions based on the
-// error content, instead of printing it out or propagating it further. Here, we
-// define a custom error type to make it possible for callers to decide what to
-// do next when our function returns an error.
+// This program uses an altered version of the code from errors4.
 //
-// Execute `rustlings hint errors6` or use the `hint` watch subcommand for a
+// This exercise uses some concepts that we won't get to until later in the
+// course, like `Box` and the `From` trait. It's not important to understand
+// them in detail right now, but you can read ahead if you like. For now, think
+// of the `Box<dyn ???>` type as an "I want anything that does ???" type, which,
+// given Rust's usual standards for runtime safety, should strike you as
+// somewhat lenient!
+//
+// In short, this particular use case for boxes is for when you want to own a
+// value and you care only that it is a type which implements a particular
+// trait. To do so, The Box is declared as of type Box<dyn Trait> where Trait is
+// the trait the compiler looks for on any value used in that context. For this
+// exercise, that context is the potential errors which can be returned in a
+// Result.
+//
+// What can we use to describe both errors? In other words, is there a trait
+// which both errors implement?
+//
+// Execute `rustlings hint errors5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
+use std::error;
+use std::error::Error;
+use std::fmt;
 use std::num::ParseIntError;
 
-// This is a custom error type that we will be using in `parse_pos_nonzero()`.
-#[derive(PartialEq, Debug)]
-enum ParsePosNonzeroError {
-    Creation(CreationError),
-    ParseInt(ParseIntError),
-}
-
-impl ParsePosNonzeroError {
-    fn from_creation(err: CreationError) -> ParsePosNonzeroError {
-        ParsePosNonzeroError::Creation(err)
-    }
-    // TODO: add another error conversion function here.
-    // fn from_parseint...
-}
-
-fn parse_pos_nonzero(s: &str) -> Result<PositiveNonzeroInteger, ParsePosNonzeroError> {
-    // TODO: change this to return an appropriate error instead of panicking
-    // when `parse()` returns an error.
-    let x: i64 = s.parse().unwrap();
-    PositiveNonzeroInteger::new(x).map_err(ParsePosNonzeroError::from_creation)
+// TODO: update the return type of `main()` to make this compile.
+fn main() -> Result<(), Box<dyn Error>> {
+    let pretend_user_input = "42";
+    let x: i64 = pretend_user_input.parse()?;
+    println!("output={:?}", PositiveNonzeroInteger::new(x)?);
+    Ok(())
 }
 
 // Don't change anything below this line.
@@ -56,39 +56,15 @@ impl PositiveNonzeroInteger {
     }
 }
 
-#[cfg(test)]
-mod test {
-    use super::*;
-
-    #[test]
-    fn test_parse_error() {
-        // We can't construct a ParseIntError, so we have to pattern match.
-        assert!(matches!(
-            parse_pos_nonzero("not a number"),
-            Err(ParsePosNonzeroError::ParseInt(_))
-        ));
-    }
-
-    #[test]
-    fn test_negative() {
-        assert_eq!(
-            parse_pos_nonzero("-555"),
-            Err(ParsePosNonzeroError::Creation(CreationError::Negative))
-        );
-    }
-
-    #[test]
-    fn test_zero() {
-        assert_eq!(
-            parse_pos_nonzero("0"),
-            Err(ParsePosNonzeroError::Creation(CreationError::Zero))
-        );
-    }
-
-    #[test]
-    fn test_positive() {
-        let x = PositiveNonzeroInteger::new(42);
-        assert!(x.is_ok());
-        assert_eq!(parse_pos_nonzero("42"), Ok(x.unwrap()));
+// This is required so that `CreationError` can implement `error::Error`.
+impl fmt::Display for CreationError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let description = match *self {
+            CreationError::Negative => "number is negative",
+            CreationError::Zero => "number is zero",
+        };
+        f.write_str(description)
     }
 }
+
+impl error::Error for CreationError {}

exercises/generics/generics1.rs

@@ -6,9 +6,8 @@
 // Execute `rustlings hint generics1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
 
 fn main() {
-    let mut shopping_list: Vec<?> = Vec::new();
+    let mut shopping_list = Vec::new();
     shopping_list.push("milk");
 }