Enum Sub 

pub enum Sub<Msg> {
    None,
    Batch(Vec<Sub<Msg>>),
    Interval {
        id: &'static str,
        duration: Duration,
        msg: Msg,
    },
}

A subscription representing a continuous effect

Subscriptions are declared each frame based on model state. The runtime manages starting/stopping subscriptions as they appear or disappear from the returned Sub.

Variants

None

No subscription

Batch(Vec<Sub<Msg>>)

Multiple subscriptions

Interval

Periodic interval timer

Emits the message at regular intervals. The id must be unique - subscriptions with the same ID are considered identical and won’t be restarted.

Fields

id: &'static str

Unique identifier for this interval

duration: Duration

Time between emissions

msg: Msg

Message to emit

Implementations

impl<Msg: Clone> Sub<Msg>

pub fn none() -> Self

Create an empty subscription

pub fn batch(subs: impl IntoIterator<Item = Sub<Msg>>) -> Self

Create a batch of subscriptions

pub fn interval(id: &'static str, duration: Duration, msg: Msg) -> Self

Create a periodic interval subscription

The message will be emitted every duration after the subscription starts.

Arguments

• id: Unique identifier. Intervals with the same ID won’t restart.
• duration: Time between message emissions
• msg: Message to emit each interval

Example

// Auto-save every 30 seconds when enabled
fn subscriptions(model: &Model) -> Sub<Msg> {
    if model.auto_save_enabled {
        Sub::interval("auto_save", Duration::from_secs(30), Msg::AutoSave)
    } else {
        Sub::none()
    }
}

impl<Msg> Sub<Msg>

pub fn is_none(&self) -> bool

Check if this is Sub::None

pub fn is_interval(&self) -> bool

Check if this is Sub::Interval

pub fn is_batch(&self) -> bool

Check if this is Sub::Batch

pub fn len(&self) -> usize

Get the number of subscriptions (1 for single, n for batch, 0 for none)

pub fn is_empty(&self) -> bool

Check if empty

Trait Implementations

impl<Msg: Clone> Clone for Sub<Msg>

fn clone(&self) -> Sub<Msg>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<Msg> Default for Sub<Msg>

fn default() -> Sub<Msg>

Returns the “default value” for a type.