Struct Environment

pub struct Environment { /* private fields */ }

The effects a layer needs but must not reach for: time and randomness.

Cloning is cheap, both sources sit behind an Arc, so an Environment is meant to be passed by value into the layers and recipes that need it and kept alongside the Database.

Example

// Production: machine clock, generator seeded from entropy.
let env = Environment::default();

// A reproducible run: the same seed replays the same sequence.
let env = Environment::with_seed(42);
let first = env.rng().next_u64();
assert_eq!(Environment::with_seed(42).rng().next_u64(), first);

Implementations

impl Environment

pub fn new(clock: Arc<dyn Clock>, rng: Arc<dyn Rng>) -> Self

Bundles a clock and a generator.

pub fn with_seed(seed: u64) -> Self

The machine clock, with a generator replaying the sequence of seed.

pub fn clock(&self) -> &Arc<dyn Clock>

The clock of this environment.

pub fn rng(&self) -> &Arc<dyn Rng>

The pseudo-random generator of this environment.

Trait Implementations

impl Clone for Environment

fn clone(&self) -> Environment

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Environment

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Environment

fn default() -> Self

Returns the “default value” for a type.