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Make Arc cloning mechanics clearer in module docs #53782

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Sep 1, 2018
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Make Arc cloning mechanics clearer in module docs #53782

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Make Arc cloning mechanics clearer in module docs
rask Aug 29, 2018
6020219
Rephrase Arc documentation changes regarding clones
rask Aug 30, 2018
bf7e324
Add clearer wording to Arc clone example code
rask Aug 31, 2018
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9 changes: 5 additions & 4 deletions src/liballoc/sync.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -49,9 +49,9 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
///
/// The type `Arc<T>` provides shared ownership of a value of type `T`,
/// allocated in the heap. Invoking [`clone`][clone] on `Arc` produces
/// a new pointer to the same value in the heap. When the last `Arc`
/// pointer to a given value is destroyed, the pointed-to value is
/// also destroyed.
/// a new pointer to the same `Arc` reference value in the heap. When the last
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It would be more accurate to say "produces a new Arc pointing to the same value in the heap". The source might make it clearer.

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Ooh it works like that! So the internal reference is cloned. Been hearing varying descriptions on how it works. I can change it to reflect that soon. Thanks for clarifying.

/// `Arc` pointer to a given value is destroyed, the pointed-to value is also
/// destroyed.
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Sounds better now!

///
/// Shared references in Rust disallow mutation by default, and `Arc` is no
/// exception: you cannot generally obtain a mutable reference to something
Expand Down Expand Up @@ -107,7 +107,8 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
/// // The two syntaxes below are equivalent.
/// let a = foo.clone();
/// let b = Arc::clone(&foo);
/// // a and b both point to the same memory location as foo.
/// // a and b both point to the same memory location where foo resides
/// // (not where the value wrapped by foo resides).
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@durka durka Aug 29, 2018 •
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In fact a, b, and foo are all separate Arcs pointing to the memory location (where the Vec resides (okay actually a couple bytes away from it, to make room for the reference counts)). So I don't think this change is necessary.

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As per your other comment, I agree, will remove this.

/// ```
///
/// The [`Arc::clone(&from)`] syntax is the most idiomatic because it conveys more explicitly
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