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strings4: remove From-based conversion

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To understand From-based conversion, an understanding of traits is
required, which we teach in a later chapter. The From trait specifically
is taught in one of the conversion exercises. So, we can safely remove
it here without users missing out on learning something important.

A specific source of confusion for users was a warning that the
conversion is useless, which appeared when using the `string_slice`
function for the expression with `.into()`. closes #2190
This commit is contained in:
Remo Senekowitsch 2026-05-19 17:29:16 +02:00
parent 60b369a2fd
commit b18a8c3036
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2 changed files with 0 additions and 11 deletions
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2
exercises/09_strings/strings4.rs
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@ -21,8 +21,6 @@ fn main() {
placeholder("rust is fun!".to_owned());
placeholder("nice weather".into());
placeholder(format!("Interpolation {}", "Station"));
// WARNING: This is byte indexing, not character indexing.

9
solutions/09_strings/strings4.rs
View File

@ -15,15 +15,6 @@ fn main() {
string("rust is fun!".to_owned());
// Here, both answers work.
// `.into()` converts a type into an expected type.
// If it is called where `String` is expected, it will convert `&str` to `String`.
string("nice weather".into());
// But if it is called where `&str` is expected, then `&str` is kept as `&str` since no conversion is needed.
// If you remove the `#[allow(…)]` line, then Clippy will tell you to remove `.into()` below since it is a useless conversion.
#[allow(clippy::useless_conversion)]
string_slice("nice weather".into());
string(format!("Interpolation {}", "Station"));
// WARNING: This is byte indexing, not character indexing.