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add note to lines docs about empty str behavior #148912

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add note to lines docs about empty str behavior #148912

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4996edc
add note to `lines` docs about empty str behavior
msmoiz Nov 13, 2025
e628b05
update language from "no lines" to "empty iterator"
msmoiz Nov 14, 2025
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11 changes: 11 additions & 0 deletions library/core/src/str/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1251,6 +1251,8 @@ impl str {
/// ending will return the same lines as an otherwise identical string
/// without a final line ending.
///
/// An empty string returns no lines.
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@Kivooeo Kivooeo Nov 13, 2025

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imho, "no lines" feels not obvious what does that mean, like, would it be better to have wording like "returns None"?

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@msmoiz msmoiz Nov 13, 2025

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Hmm, I think that might be a bit confusing since the method itself returns a Lines object instead of an Option and saying "returns None" makes it sound like it returns an Option. A few possible alternatives:

  • "An empty string returns an empty iterator"
  • "Returns an empty iterator when called on an empty string"
  • "Empty strings produce no lines"

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@Kivooeo Kivooeo Nov 13, 2025

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Ah, sure it's an iterator

Empty iterator instead None then, should be clear enough

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@msmoiz msmoiz Nov 14, 2025

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Okay cool, updated

///
/// # Examples
///
/// Basic usage:
Expand Down Expand Up @@ -1281,6 +1283,15 @@ impl str {
///
/// assert_eq!(None, lines.next());
/// ```
///
/// An empty string returns no lines:
///
/// ```
/// let text = "";
/// let mut lines = text.lines();
///
/// assert_eq!(lines.next(), None);
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn lines(&self) -> Lines<'_> {
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