Explain LazyCell in core::cell overview · model-checking/verify-rust-std@a198721 (original) (raw)
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`//!
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`` //! The corresponding [Sync] version of OnceCell<T> is [OnceLock<T>].
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`//!
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//! ## LazyCell<T, F>
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//!
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//! A common pattern with OnceCell is, for a given OnceCell, to use the same function on every
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//! call to [OnceCell::get_or_init] with that cell. This is what is offered by [LazyCell],
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//! which pairs cells of T with functions of F, and always calls F before it yields &T.
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//! This happens implicitly by simply attempting to dereference the LazyCell to get its contents,
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//! so its use is much more transparent with a place which has been initialized by a constant.
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//!
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//! More complicated patterns that don't fit this description can be built on OnceCell<T> instead.
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//!
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//! LazyCell works by providing an implementation of impl Deref that calls the function,
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//! so you can just use it by dereference (e.g. *lazy_cell or lazy_cell.deref()).
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//!
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//! The corresponding [Sync] version of LazyCell<T, F> is [LazyLock<T, F>].
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`//!
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`//! # When to choose interior mutability
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`//!
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`` //! [RwLock<T>]: ../../std/sync/struct.RwLock.html
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`` //! [Mutex<T>]: ../../std/sync/struct.Mutex.html
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`` //! [OnceLock<T>]: ../../std/sync/struct.OnceLock.html
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//! [LazyLock<T, F>]: ../../std/sync/struct.LazyLock.html
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`` //! [Sync]: ../../std/marker/trait.Sync.html
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`` //! [atomic]: crate::sync::atomic
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``