From 85d268f98577833acaea02ff820916b58cec4c4f Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Thu, 9 Jan 2025 23:53:05 +0100
Subject: [PATCH 1/8] Add target solution
---
solutions/13_error_handling/errors7.rs | 102 +++++++++++++++++++++++++
1 file changed, 102 insertions(+)
create mode 100644 solutions/13_error_handling/errors7.rs
diff --git a/solutions/13_error_handling/errors7.rs b/solutions/13_error_handling/errors7.rs
new file mode 100644
index 00000000..61464042
--- /dev/null
+++ b/solutions/13_error_handling/errors7.rs
@@ -0,0 +1,102 @@
+// Using catch-all error types like `Box<dyn 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.
+
+use std::num::ParseIntError;
+
+#[derive(PartialEq, Debug)]
+enum CreationError {
+ Negative,
+ Zero,
+}
+
+// A custom error type that we will be using in `PositiveNonzeroInteger::parse`.
+#[derive(PartialEq, Debug)]
+enum ParsePosNonzeroError {
+ Creation(CreationError),
+ ParseInt(ParseIntError),
+}
+
+impl ParsePosNonzeroError {
+ fn from_creation(err: CreationError) -> Self {
+ Self::Creation(err)
+ }
+
+ fn from_parse_int(err: ParseIntError) -> Self {
+ Self::ParseInt(err)
+ }
+}
+
+impl From<ParseIntError> for ParsePosNonzeroError {
+ fn from(err: ParseIntError) -> Self {
+ ParsePosNonzeroError::from_parse_int(err)
+ }
+}
+
+impl From<CreationError> for ParsePosNonzeroError {
+ fn from(err: CreationError) -> Self {
+ ParsePosNonzeroError::from_creation(err)
+ }
+}
+
+#[derive(PartialEq, Debug)]
+struct PositiveNonzeroInteger(u64);
+
+impl PositiveNonzeroInteger {
+ fn new(value: i64) -> Result<Self, CreationError> {
+ match value {
+ x if x < 0 => Err(CreationError::Negative),
+ 0 => Err(CreationError::Zero),
+ x => Ok(Self(x as u64)),
+ }
+ }
+
+ fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
+ // Return an appropriate error instead of panicking when `parse()`
+ // returns an error.
+ let x: i64 = s.parse()?;
+ Self::new(x)?
+ }
+}
+
+fn main() {
+ // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ #[test]
+ fn test_parse_error() {
+ assert!(matches!(
+ PositiveNonzeroInteger::parse("not a number"),
+ Err(ParsePosNonzeroError::ParseInt(_)),
+ ));
+ }
+
+ #[test]
+ fn test_negative() {
+ assert_eq!(
+ PositiveNonzeroInteger::parse("-555"),
+ Err(ParsePosNonzeroError::Creation(CreationError::Negative)),
+ );
+ }
+
+ #[test]
+ fn test_zero() {
+ assert_eq!(
+ PositiveNonzeroInteger::parse("0"),
+ Err(ParsePosNonzeroError::Creation(CreationError::Zero)),
+ );
+ }
+
+ #[test]
+ fn test_positive() {
+ let x = PositiveNonzeroInteger::new(42).unwrap();
+ assert_eq!(x.0, 42);
+ assert_eq!(PositiveNonzeroInteger::parse("42"), Ok(x));
+ }
+}
From 5cccae3673c9539bd0a8d3d242b8f3053f426939 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Fri, 10 Jan 2025 00:00:20 +0100
Subject: [PATCH 2/8] Update info.toml
---
rustlings-macros/info.toml | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml
index e7055981..d939b74b 100644
--- a/rustlings-macros/info.toml
+++ b/rustlings-macros/info.toml
@@ -721,6 +721,13 @@ can then use the `?` operator to return early.
Read more about `map_err()` in the `std::result` documentation:
https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
+[[exercises]]
+name = "errors7"
+dir = "13_error_handling"
+hint = """
+TODO
+"""
+
# Generics
[[exercises]]
From cca2e226ffbc332bd2151d5f7bf01c7aed004839 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Fri, 10 Jan 2025 00:03:30 +0100
Subject: [PATCH 3/8] Add draft of exercise file
---
exercises/13_error_handling/errors7.rs | 97 ++++++++++++++++++++++++++
1 file changed, 97 insertions(+)
create mode 100644 exercises/13_error_handling/errors7.rs
diff --git a/exercises/13_error_handling/errors7.rs b/exercises/13_error_handling/errors7.rs
new file mode 100644
index 00000000..4d9affbb
--- /dev/null
+++ b/exercises/13_error_handling/errors7.rs
@@ -0,0 +1,97 @@
+// TODOUsing catch-all error types like `Box<dyn 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.
+
+use std::num::ParseIntError;
+
+#[derive(PartialEq, Debug)]
+enum CreationError {
+ Negative,
+ Zero,
+}
+
+// A custom error type that we will be using in `PositiveNonzeroInteger::parse`.
+#[derive(PartialEq, Debug)]
+enum ParsePosNonzeroError {
+ Creation(CreationError),
+ ParseInt(ParseIntError),
+}
+
+impl ParsePosNonzeroError {
+ fn from_creation(err: CreationError) -> Self {
+ Self::Creation(err)
+ }
+
+ fn from_parse_int(err: ParseIntError) -> Self {
+ Self::ParseInt(err)
+ }
+}
+
+// TODO Implement From trait for ParseIntError and CreationError
+// impl From<ParseIntError> for ParsePosNonzeroError {
+// fn from(err: ParseIntError) -> Self {
+// ???
+// }
+// }
+
+#[derive(PartialEq, Debug)]
+struct PositiveNonzeroInteger(u64);
+
+impl PositiveNonzeroInteger {
+ fn new(value: i64) -> Result<Self, CreationError> {
+ match value {
+ x if x < 0 => Err(CreationError::Negative),
+ 0 => Err(CreationError::Zero),
+ x => Ok(Self(x as u64)),
+ }
+ }
+
+ fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
+ // Return an appropriate error instead of panicking when `parse()`
+ // returns an error.
+ let x: i64 = s.parse()?;
+ Self::new(x)?
+ }
+}
+
+fn main() {
+ // You can optionally experiment here.
+}
+
+#[cfg(test)]
+mod test {
+ use super::*;
+
+ #[test]
+ fn test_parse_error() {
+ assert!(matches!(
+ PositiveNonzeroInteger::parse("not a number"),
+ Err(ParsePosNonzeroError::ParseInt(_)),
+ ));
+ }
+
+ #[test]
+ fn test_negative() {
+ assert_eq!(
+ PositiveNonzeroInteger::parse("-555"),
+ Err(ParsePosNonzeroError::Creation(CreationError::Negative)),
+ );
+ }
+
+ #[test]
+ fn test_zero() {
+ assert_eq!(
+ PositiveNonzeroInteger::parse("0"),
+ Err(ParsePosNonzeroError::Creation(CreationError::Zero)),
+ );
+ }
+
+ #[test]
+ fn test_positive() {
+ let x = PositiveNonzeroInteger::new(42).unwrap();
+ assert_eq!(x.0, 42);
+ assert_eq!(PositiveNonzeroInteger::parse("42"), Ok(x));
+ }
+}
From 213a32b378869a599689a22514362ad355da8b69 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Fri, 10 Jan 2025 00:04:10 +0100
Subject: [PATCH 4/8] Update
---
rustlings-macros/info.toml | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml
index d939b74b..6d0764af 100644
--- a/rustlings-macros/info.toml
+++ b/rustlings-macros/info.toml
@@ -725,7 +725,7 @@ https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
name = "errors7"
dir = "13_error_handling"
hint = """
-TODO
+TODO Add hint and place after traits exercise
"""
# Generics
From 72fbb10e2cc84d0e4f2316c35c313d965403ecf3 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Fri, 10 Jan 2025 10:50:30 +0100
Subject: [PATCH 5/8] Move errors7 after traits1
---
rustlings-macros/info.toml | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml
index 6d0764af..f1f2ecef 100644
--- a/rustlings-macros/info.toml
+++ b/rustlings-macros/info.toml
@@ -721,13 +721,6 @@ can then use the `?` operator to return early.
Read more about `map_err()` in the `std::result` documentation:
https://doc.rust-lang.org/std/result/enum.Result.html#method.map_err"""
-[[exercises]]
-name = "errors7"
-dir = "13_error_handling"
-hint = """
-TODO Add hint and place after traits exercise
-"""
-
# Generics
[[exercises]]
@@ -763,6 +756,13 @@ https://doc.rust-lang.org/book/ch10-02-traits.html
The `+` operator can concatenate a `String` with a `&str`."""
+[[exercises]]
+name = "errors7"
+dir = "13_error_handling"
+hint = """
+More about relatio between try operator and From Trait:
+https://doc.rust-lang.org/std/convert/trait.From.html#examples"""
+
[[exercises]]
name = "traits2"
dir = "15_traits"
From d8babf9a5367fd24addafa05c1fba82498959a47 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Sun, 12 Jan 2025 11:50:18 +0100
Subject: [PATCH 6/8] Update description
---
exercises/13_error_handling/errors7.rs | 19 +++++++++++--------
rustlings-macros/info.toml | 2 +-
solutions/13_error_handling/errors7.rs | 14 +++++++-------
3 files changed, 19 insertions(+), 16 deletions(-)
diff --git a/exercises/13_error_handling/errors7.rs b/exercises/13_error_handling/errors7.rs
index 4d9affbb..446f48ec 100644
--- a/exercises/13_error_handling/errors7.rs
+++ b/exercises/13_error_handling/errors7.rs
@@ -1,8 +1,8 @@
-// TODOUsing catch-all error types like `Box<dyn 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.
+// While defining and using a custom error type in library code is recomended
+// the ergonomics of the map_err approach presented in errors6 is suboptimal.
+// The growing codebase could quickly become obfuscated by error conversions
+// sprinkled here and there. Fortunetly, using traits we just learned about,
+// we can use one more Rust feature to fix that.
use std::num::ParseIntError;
@@ -29,13 +29,16 @@ impl ParsePosNonzeroError {
}
}
-// TODO Implement From trait for ParseIntError and CreationError
+// TODO Implement From trait for ParseIntError
// impl From<ParseIntError> for ParsePosNonzeroError {
// fn from(err: ParseIntError) -> Self {
// ???
// }
// }
+// TODO Implement From trait for CreationError
+// ...
+
#[derive(PartialEq, Debug)]
struct PositiveNonzeroInteger(u64);
@@ -49,9 +52,9 @@ impl PositiveNonzeroInteger {
}
fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
- // Return an appropriate error instead of panicking when `parse()`
- // returns an error.
+ // Don't change this line
let x: i64 = s.parse()?;
+ // Don't change this line
Self::new(x)?
}
}
diff --git a/rustlings-macros/info.toml b/rustlings-macros/info.toml
index f1f2ecef..54705b61 100644
--- a/rustlings-macros/info.toml
+++ b/rustlings-macros/info.toml
@@ -760,7 +760,7 @@ The `+` operator can concatenate a `String` with a `&str`."""
name = "errors7"
dir = "13_error_handling"
hint = """
-More about relatio between try operator and From Trait:
+More about relation between try operator and the From trait:
https://doc.rust-lang.org/std/convert/trait.From.html#examples"""
[[exercises]]
diff --git a/solutions/13_error_handling/errors7.rs b/solutions/13_error_handling/errors7.rs
index 61464042..534d13ed 100644
--- a/solutions/13_error_handling/errors7.rs
+++ b/solutions/13_error_handling/errors7.rs
@@ -1,8 +1,8 @@
-// Using catch-all error types like `Box<dyn 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.
+// While defining and using a custom error type in library code is recomended
+// the ergonomics of the map_err approach presented in errors6 is suboptimal.
+// The growing codebase could quickly become obfuscated by error conversions
+// sprinkled here and there. Fortunetly, using traits we just learned about,
+// we can use one more Rust feature to fix that.
use std::num::ParseIntError;
@@ -54,9 +54,9 @@ impl PositiveNonzeroInteger {
}
fn parse(s: &str) -> Result<Self, ParsePosNonzeroError> {
- // Return an appropriate error instead of panicking when `parse()`
- // returns an error.
+ // Don't change this line
let x: i64 = s.parse()?;
+ // Don't change this line
Self::new(x)?
}
}
From 2e29a61afaf6f5722b0a82f2a2ee3ff90124269a Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Sun, 12 Jan 2025 15:56:07 +0100
Subject: [PATCH 7/8] Fix bug
---
exercises/13_error_handling/errors7.rs | 2 +-
solutions/13_error_handling/errors7.rs | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/exercises/13_error_handling/errors7.rs b/exercises/13_error_handling/errors7.rs
index 446f48ec..5e401619 100644
--- a/exercises/13_error_handling/errors7.rs
+++ b/exercises/13_error_handling/errors7.rs
@@ -55,7 +55,7 @@ impl PositiveNonzeroInteger {
// Don't change this line
let x: i64 = s.parse()?;
// Don't change this line
- Self::new(x)?
+ Ok(Self::new(x)?)
}
}
diff --git a/solutions/13_error_handling/errors7.rs b/solutions/13_error_handling/errors7.rs
index 534d13ed..b61e657d 100644
--- a/solutions/13_error_handling/errors7.rs
+++ b/solutions/13_error_handling/errors7.rs
@@ -57,7 +57,7 @@ impl PositiveNonzeroInteger {
// Don't change this line
let x: i64 = s.parse()?;
// Don't change this line
- Self::new(x)?
+ Ok(Self::new(x)?)
}
}
From 0b8bb4b935053e4f80505940583c045930176478 Mon Sep 17 00:00:00 2001
From: Grzegorz Dziadkiewicz <grzegorzdziadkiewicz@gmail.com>
Date: Sun, 12 Jan 2025 16:12:17 +0100
Subject: [PATCH 8/8] Update dev/Cargo.toml
---
dev/Cargo.toml | 2 ++
1 file changed, 2 insertions(+)
diff --git a/dev/Cargo.toml b/dev/Cargo.toml
index 29a557a0..4f6c7424 100644
--- a/dev/Cargo.toml
+++ b/dev/Cargo.toml
@@ -118,6 +118,8 @@ bin = [
{ name = "generics2_sol", path = "../solutions/14_generics/generics2.rs" },
{ name = "traits1", path = "../exercises/15_traits/traits1.rs" },
{ name = "traits1_sol", path = "../solutions/15_traits/traits1.rs" },
+ { name = "errors7", path = "../exercises/13_error_handling/errors7.rs" },
+ { name = "errors7_sol", path = "../solutions/13_error_handling/errors7.rs" },
{ name = "traits2", path = "../exercises/15_traits/traits2.rs" },
{ name = "traits2_sol", path = "../solutions/15_traits/traits2.rs" },
{ name = "traits3", path = "../exercises/15_traits/traits3.rs" },