Changelog

1.9

• Added an atomic-polyfill optional dependency to compile race on platforms without atomics

1.8.0

• Add try_insert API -- a version of set that returns a reference.

1.7.2

• Improve code size when using parking_lot feature.

1.7.1

• Fix race::OnceBox<T> to also impl Default even if T doesn't impl Default.

1.7.0

• Hide the race module behind (default) race feature. Turns out that adding race by default was a breaking change on some platforms without atomics. In this release, we make the module opt-out. Technically, this is a breaking change for those who use race with no_default_features. Given that the race module itself only several days old, the breakage is deemed acceptable.

1.6.0

• Add Lazy::into_value
• Stabilize once_cell::race module for “first one wins” no_std-compatible initialization flavor.
• Migrate from deprecated compare_and_swap to compare_exchange.

1.5.2

• OnceBox API uses Box<T>. This a breaking change to unstable API.

1.5.1

• MSRV is increased to 1.36.0.
• document once_cell::race module.
• introduce alloc feature for OnceBox.
• fix OnceBox::set.

1.5.0

• add new once_cell::race module for “first one wins” no_std-compatible initialization flavor. The API is provisional, subject to change and is gated by the unstable cargo feature.

1.4.1

• upgrade parking_lot to 0.11.0
• make sync::OnceCell<T> pass https://doc.rust-lang.org/nomicon/dropck.html#an-escape-hatch[dropck] with parking_lot feature enabled. This fixes a (minor) semver-incompatible changed introduced in 1.4.0

1.4.0

• upgrade parking_lot to 0.10 (note that this bumps MSRV with parking_lot feature enabled to 1.36.0).
• add OnceCell::take.
• upgrade crossbeam utils (private dependency) to 0.7.

1.3.1

• remove unnecessary F: fmt::Debug bound from impl fmt::Debug for Lazy<T, F>.

1.3.0

• Lazy<T> now implements DerefMut.
• update implementation according to the latest changes in std.

1.2.0

• add sync::OnceCell::get_unchecked.

1.1.0

• implement Default for Lazy: it creates an empty Lazy<T> which is initialized with T::default on first access.
• add OnceCell::get_mut.

1.0.2

• actually add #![no_std] attribute if std feature is not enabled.

1.0.1

• fix unsoundness in Lazy<T> if the initializing function panics. Thanks @xfix!
• implement RefUnwindSafe for Lazy.
• share more code between std and parking_lot implementations.
• add F.A.Q section to the docs.

1.0.0

• remove parking_lot from the list of default features.
• add std default feature. Without std, only unsync module is supported.
• implement Eq for OnceCell.
• fix wrong Sync bound on sync::Lazy.
• run the whole test suite with miri.

0.2.7

• New implementation of sync::OnceCell if parking_lot feature is disabled. It now employs a hand-rolled variant of std::sync::Once.
• sync::OnceCell::get_or_try_init works without parking_lot as well!
• document the effects of parking_lot feature: same performance but smaller types.

0.2.6

• Updated Lazy's Deref impl to requires only FnOnce instead of Fn

0.2.5

• Lazy requires only FnOnce instead of Fn

0.2.4

• nicer fmt::Debug implementation

0.2.3

• update parking_lot to 0.9.0
• fix stacked borrows violation in unsync::OnceCell::get
• implement Clone for sync::OnceCell<T> where T: Clone

0.2.2

• add OnceCell::into_inner which consumes a cell and returns an option

0.2.1

• implement sync::OnceCell::get_or_try_init if parking_lot feature is enabled
• switch internal unsafe implementation of sync::OnceCell from Once to Mutex
• sync::OnceCell::get_or_init is twice as fast if cell is already initialized
• implement std::panic::RefUnwindSafe and std::panic::UnwindSafe for OnceCell
• better document behavior around panics

0.2.0

• MSRV is now 1.31.1
• Lazy::new and OnceCell::new are now const-fns
• unsync_lazy and sync_lazy macros are removed

0.1.8

• update crossbeam-utils to 0.6
• enable bors-ng

0.1.7

• cells implement PartialEq and From
• MSRV is down to 1.24.1
• update parking_lot to 0.7.1

0.1.6

• unsync::OnceCell<T> is Clone if T is Clone.

0.1.5

• No changelog until this point :(