Struct Pref 

pub struct Pref<T>
where
    T: PrefValue,
{ /* private fields */ }

A typed, persisted, reactive setting (docs/settings.md), declared once as a static:

pub static SNAP: Pref<bool> = Pref::new("sketch.snap", || true);

The signal behind it is created on the UI thread on first use, seeded from the store (or the default when the key is absent or unparsable), and lives for the process. Pref is Copy, so a row or a closure takes it by value.

Implementations

impl<T> Pref<T>

where T: PrefValue,

pub const fn new(key: &'static str, default: fn() -> T) -> Pref<T>

Declare a pref under key with a default. default is a function so the static holds no value that needs Sync (|| String::new(), || Unit::Celsius).

pub const fn env(self, var: &'static str) -> Pref<T>

The env-wins rule: while var is set in the process environment the stored value is ignored for this run (the signal seeds from the default), so a day launch --env run and every CI variant loop stay deterministic whatever an earlier run persisted. Writes still persist.

pub fn key(&self) -> &'static str

The store key.

pub fn default(&self) -> T

The default value.

pub fn env_forced(&self) -> bool

Whether the env-wins variable is set for this run.

pub fn signal(&self) -> Signal<T>

The signal behind the pref: hand it to a control or a binding. Created and seeded on first call.

pub fn get(&self) -> T

Tracked read: subscribes the running computation.

pub fn get_untracked(&self) -> T

Untracked read.

pub fn set(&self, value: T)

Write: the signal, which persists (see Self::signal). An unchanged value is a no-op.

pub fn reset(&self)

Back to the default: the key leaves the store.

pub fn is_default(&self) -> bool

Whether the current value equals the default.

pub fn watch(&self, f: impl Fn(&T) + 'static)

Run f on every later change (not on subscription), in the current reactive scope.

Trait Implementations

impl<T> Clone for Pref<T>

where T: PrefValue,

fn clone(&self) -> Pref<T>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Copy for Pref<T>

where T: PrefValue,