record progress: clippy, macros

.rustlings-state.txt

@@ -1,6 +1,6 @@
 DON'T EDIT THIS FILE!
 
-macros1
+using_as
 
 intro1
 intro2
@@ -83,4 +83,11 @@ arc1
 cow1
 threads1
 threads2
-threads3
+threads3
+macros1
+macros2
+macros3
+macros4
+clippy1
+clippy2
+clippy3

exercises/21_macros/macros1.rs

@@ -6,5 +6,5 @@ macro_rules! my_macro {
 
 fn main() {
     // TODO: Fix the macro call.
-    my_macro();
+    my_macro!();
 }

exercises/21_macros/macros2.rs

@@ -1,10 +1,9 @@
-fn main() {
-    my_macro!();
-}
-
-// TODO: Fix the compiler error by moving the whole definition of this macro.
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
     };
 }
+
+fn main() {
+    my_macro!();
+}

exercises/21_macros/macros3.rs

@@ -1,5 +1,6 @@
 // TODO: Fix the compiler error without taking the macro definition out of this
 // module.
+#[macro_use]
 mod macros {
     macro_rules! my_macro {
         () => {

exercises/21_macros/macros4.rs

@@ -3,10 +3,10 @@
 macro_rules! my_macro {
     () => {
         println!("Check out my macro!");
-    }
+    };
     ($val:expr) => {
         println!("Look at this other macro: {}", $val);
-    }
+    };
 }
 
 fn main() {

exercises/22_clippy/clippy1.rs

@@ -4,9 +4,11 @@
 // For these exercises, the code will fail to compile when there are Clippy
 // warnings. Check Clippy's suggestions from the output to solve the exercise.
 
+use std::f32::consts;
+
 fn main() {
     // TODO: Fix the Clippy lint in this line.
-    let pi = 3.14;
+    let pi = consts::PI;
     let radius: f32 = 5.0;
 
     let area = pi * radius.powi(2);

exercises/22_clippy/clippy2.rs

@@ -2,7 +2,7 @@ fn main() {
     let mut res = 42;
     let option = Some(12);
     // TODO: Fix the Clippy lint.
-    for x in option {
+    if let Some(x) = option {
         res += x;
     }
 

exercises/22_clippy/clippy3.rs

@@ -6,22 +6,22 @@
 fn main() {
     let my_option: Option<()> = None;
     if my_option.is_none() {
-        println!("{:?}", my_option.unwrap());
+        println!("{:?}", my_option);
     }
 
     let my_arr = &[
-        -1, -2, -3
+        -1, -2, -3,
         -4, -5, -6
     ];
     println!("My array! Here it is: {my_arr:?}");
 
-    let my_empty_vec = vec![1, 2, 3, 4, 5].resize(0, 5);
+    let mut my_empty_vec = vec![1, 2, 3, 4, 5];
+    my_empty_vec.clear();
     println!("This Vec is empty, see? {my_empty_vec:?}");
 
     let mut value_a = 45;
     let mut value_b = 66;
     // Let's swap these two!
-    value_a = value_b;
+    std::mem::swap(&mut value_a, &mut value_b);
-    value_b = value_a;
     println!("value a: {value_a}; value b: {value_b}");
 }

exercises/23_conversions/as_ref_mut.rs

@@ -3,21 +3,19 @@
 // https://doc.rust-lang.org/std/convert/trait.AsMut.html, respectively.
 
 // Obtain the number of bytes (not characters) in the given argument.
-// TODO: Add the `AsRef` trait appropriately as a trait bound.
+fn byte_counter<T>(arg: T) -> usize where T: AsRef<str>
-fn byte_counter<T>(arg: T) -> usize {
+{
     arg.as_ref().as_bytes().len()
 }
 
 // Obtain the number of characters (not bytes) in the given argument.
-// TODO: Add the `AsRef` trait appropriately as a trait bound.
+fn char_counter<T: AsRef<str>>(arg: T) -> usize {
-fn char_counter<T>(arg: T) -> usize {
     arg.as_ref().chars().count()
 }
 
 // Squares a number using `as_mut()`.
-// TODO: Add the appropriate trait bound.
+fn num_sq<T: AsMut<u32>>(arg: &mut T) {
-fn num_sq<T>(arg: &mut T) {
+    *arg.as_mut() = arg.as_mut().pow(2);
-    // TODO: Implement the function body.
 }
 
 fn main() {

exercises/23_conversions/from_into.rs

@@ -20,7 +20,7 @@ impl Default for Person {
     }
 }
 
-// TODO: Complete this `From` implementation to be able to parse a `Person`
+// Complete this `From` implementation to be able to parse a `Person`
 // out of a string in the form of "Mark,20".
 // Note that you'll need to parse the age component into a `u8` with something
 // like `"4".parse::<u8>()`.
@@ -34,7 +34,31 @@ impl Default for Person {
 // 5. Parse the second element from the split operation into a `u8` as the age.
 // 6. If parsing the age fails, return the default of `Person`.
 impl From<&str> for Person {
-    fn from(s: &str) -> Self {}
+    fn from(s: &str) -> Self {
+        let elements: Vec<&str> = s.split(",").collect();
+
+        match elements.as_slice() {
+            [a, b] => {
+                if let Ok(age) = b.parse::<u8>() {
+                    let name = a.parse().unwrap();
+                    if name == "" {
+                        return Person {
+                            name: String::from("John"),
+                            age: age,
+                        };
+                    }
+                    return Person {
+                        name: name,
+                        age: age,
+                    };
+                };
+                Person::default()
+            }
+            &_ => {
+                Person::default()
+            }
+        }
+    }
 }
 
 fn main() {

solutions/21_macros/macros1.rs

@@ -1,4 +1,10 @@
-fn main() {
+macro_rules! my_macro {
-    // DON'T EDIT THIS SOLUTION FILE!
+    () => {
-    // It will be automatically filled after you finish the exercise.
+        println!("Check out my macro!");
+    };
+}
+
+fn main() {
+    my_macro!();
+    //      ^
 }

solutions/21_macros/macros2.rs

@@ -1,4 +1,10 @@
-fn main() {
+// Moved the macro definition to be before its call.
-    // DON'T EDIT THIS SOLUTION FILE!
+macro_rules! my_macro {
-    // It will be automatically filled after you finish the exercise.
+    () => {
+        println!("Check out my macro!");
+    };
+}
+
+fn main() {
+    my_macro!();
 }

solutions/21_macros/macros3.rs

@@ -1,4 +1,13 @@
-fn main() {
+// Added the attribute `macro_use` attribute.
-    // DON'T EDIT THIS SOLUTION FILE!
+#[macro_use]
-    // It will be automatically filled after you finish the exercise.
+mod macros {
+    macro_rules! my_macro {
+        () => {
+            println!("Check out my macro!");
+        };
+    }
+}
+
+fn main() {
+    my_macro!();
 }

solutions/21_macros/macros4.rs

@@ -1,4 +1,15 @@
-fn main() {
+// Added semicolons to separate the macro arms.
-    // DON'T EDIT THIS SOLUTION FILE!
+#[rustfmt::skip]
-    // It will be automatically filled after you finish the exercise.
+macro_rules! my_macro {
+    () => {
+        println!("Check out my macro!");
+    };
+    ($val:expr) => {
+        println!("Look at this other macro: {}", $val);
+    };
+}
+
+fn main() {
+    my_macro!();
+    my_macro!(7777);
 }

solutions/22_clippy/clippy1.rs

@@ -1,4 +1,17 @@
+// The Clippy tool is a collection of lints to analyze your code so you can
+// catch common mistakes and improve your Rust code.
+//
+// For these exercises, the code will fail to compile when there are Clippy
+// warnings. Check Clippy's suggestions from the output to solve the exercise.
+
+use std::f32::consts::PI;
+
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
+    // Use the more accurate `PI` constant.
-    // It will be automatically filled after you finish the exercise.
+    let pi = PI;
+    let radius: f32 = 5.0;
+
+    let area = pi * radius.powi(2);
+
+    println!("The area of a circle with radius {radius:.2} is {area:.5}");
 }

solutions/22_clippy/clippy2.rs

@@ -1,4 +1,10 @@
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
+    let mut res = 42;
-    // It will be automatically filled after you finish the exercise.
+    let option = Some(12);
+    // Use `if-let` instead of iteration.
+    if let Some(x) = option {
+        res += x;
+    }
+
+    println!("{res}");
 }

solutions/22_clippy/clippy3.rs

@@ -1,4 +1,31 @@
+use std::mem;
+
+#[rustfmt::skip]
+#[allow(unused_variables, unused_assignments)]
 fn main() {
-    // DON'T EDIT THIS SOLUTION FILE!
+    let my_option: Option<()> = None;
-    // It will be automatically filled after you finish the exercise.
+    // `unwrap` of an `Option` after checking if it is `None` will panic.
+    // Use `if-let` instead.
+    if let Some(value) = my_option {
+        println!("{value:?}");
+    }
+
+    // A comma was missing.
+    let my_arr = &[
+        -1, -2, -3,
+        -4, -5, -6,
+    ];
+    println!("My array! Here it is: {:?}", my_arr);
+
+    let mut my_empty_vec = vec![1, 2, 3, 4, 5];
+    // `resize` mutates a vector instead of returning a new one.
+    // `resize(0, …)` clears a vector, so it is better to use `clear`.
+    my_empty_vec.clear();
+    println!("This Vec is empty, see? {my_empty_vec:?}");
+
+    let mut value_a = 45;
+    let mut value_b = 66;
+    // Use `mem::swap` to correctly swap two values.
+    mem::swap(&mut value_a, &mut value_b);
+    println!("value a: {}; value b: {}", value_a, value_b);
 }