Struct Signal 

pub struct Signal<T>
where
    T: Clone + PartialEq,
{ /* private fields */ }

A reactive signal handle.

Allows reading, writing, and subscribing to changes. Implements Copy for ergonomic use; all copies share the same underlying state.

SAFETY: The inner pointer is allocated via Box::leak and lives for the entire program. This is safe in single-threaded WASM contexts where no concurrent access can occur.

Implementations

impl<T> Signal<T>

where T: Clone + PartialEq,

Implementation of reactive signal operations.

pub fn new(value: T) -> Self

Creates a new Signal with the given initial value.

The inner state is allocated via Box::leak and lives for the remainder of the program. This is safe in single-threaded WASM contexts where no concurrent access can occur.

Arguments

• T - The initial value of the signal.

Returns

• Signal<T> - A handle to the newly created reactive signal.

pub fn get(&self) -> T

Returns the current value of the signal.

Returns

• T - The current value of the signal.

pub fn try_get(&self) -> Option<T>

Attempts to return the current value of the signal without panicking.

Returns

• Some(T) - The current value if the borrow succeeds.
• None - If the inner value is already mutably borrowed.

pub fn subscribe<F>(&self, callback: F)

where F: FnMut() + 'static,

Subscribes a callback to be invoked when the signal changes.

Arguments

• FnMut() + 'static - The callback to invoke when the signal changes.

pub fn replace_subscribe<F>(&self, callback: F)

where F: FnMut() + 'static,

Replaces all listeners with a single new callback.

Unlike subscribe, which appends a listener, this method clears any existing listeners first and then adds the new one. This prevents listener accumulation across re-renders: each signal is guaranteed to have at most one active listener at any time, eliminating cascading set() calls that would otherwise grow exponentially.

Arguments

• FnMut() + 'static - The callback to invoke when the signal changes.

pub fn clear_listeners(&self)

Removes all subscribed listeners from this signal and marks it as inactive. After calling this method, subsequent set() and try_set() calls become complete no-ops: the value is not updated, no listeners are invoked, and schedule_signal_update() is not called. This is used during hook context cleanup when a match arm switch discards old signals, ensuring that stale setInterval closures referencing these signals become entirely harmless.

pub fn set(&self, value: T)

Sets the value of the signal and notifies listeners.

If the signal has been marked as inactive (via clear_listeners()), this method is a complete no-op: the value is not updated, no listeners are invoked, and no global update is scheduled.

If the new value is equal to the current value, no update is performed and no listeners are notified. This prevents unnecessary re-renders and avoids cascading no-op updates through intermediate signal chains.

Arguments

• T - The new value to assign to the signal.

pub fn set_silent(&self, value: T)

Sets the value of the signal and notifies listeners without scheduling a global DOM update dispatch.

This is identical to set except it does not call schedule_signal_update(), meaning no __euv_signal_update__ event will be dispatched. Use this for internal bookkeeping signals whose changes should not trigger DynamicNode re-renders.

When to use

Prefer set in almost all cases. Only use set_silent when the signal change is guaranteed not to affect any DynamicNode output (e.g., internal guard flags, derived-value caches already at the correct value, or within a with_suppressed_updates block where the caller takes responsibility for batching the update).

If the new value is equal to the current value, no update is performed and no listeners are notified.

If the signal has been marked as inactive (via clear_listeners()), this method is a complete no-op.

pub fn try_set(&self, value: T) -> bool

Attempts to set the value of the signal and notify listeners without panicking.

If the new value is equal to the current value, no update is performed.

Arguments

• T - The new value to assign to the signal.

Returns

• bool - true if the value was successfully updated and listeners were notified, false if unchanged or inactive.

Trait Implementations

impl<T> AsNode for Signal<T>

where T: Clone + PartialEq + Display + 'static,

Converts a signal into a reactive text virtual node.

fn as_node(&self) -> Option<VirtualNode>

Converts this value into a VirtualNode, if possible.

impl<T> AsReactiveText for Signal<T>

where T: Clone + PartialEq + Display + 'static,

Converts a signal into a reactive text node with listener wiring.

fn as_reactive_text(&self) -> VirtualNode

Converts this value into a VirtualNode::Text with reactive signal binding.

impl<T> Clone for Signal<T>

where T: Clone + PartialEq,

Clones the signal, sharing the same inner state.

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T> Deref for Signal<T>

where T: Clone + PartialEq,

Prevents direct dereference of a signal to enforce explicit API usage.

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T> DerefMut for Signal<T>

where T: Clone + PartialEq,

Prevents direct mutable dereference of a signal to enforce explicit API usage.

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl<T> IntoNode for Signal<T>

where T: Clone + PartialEq + Display + 'static,

Converts a signal into a reactive text virtual node via IntoNode.

fn into_node(self) -> VirtualNode

Converts this value into a VirtualNode by consuming it.

impl IntoReactiveString for Signal<String>

Converts a string signal into a reactive string by resolving its current value.

fn into_reactive_string(self) -> String

Converts this value into its string representation for attribute storage.

impl IntoReactiveString for Signal<bool>

Converts a bool signal into a reactive string by resolving its current value.

fn into_reactive_string(self) -> String

Converts this value into its string representation for attribute storage.

impl IntoReactiveValue for Signal<String>

Converts a string signal into a reactive attribute value.

fn into_reactive_value(self) -> AttributeValue

Converts this value into an AttributeValue, wrapping signals for reactive updates or converting static values to text.

impl IntoReactiveValue for Signal<bool>

Converts a mutable bool signal into a reactive attribute value.

The signal is mapped to a Signal<String> that yields "true" or "false", enabling boolean attributes like checked to reactively update the DOM.

fn into_reactive_value(self) -> AttributeValue

Converts this value into an AttributeValue, wrapping signals for reactive updates or converting static values to text.

impl<T> Copy for Signal<T>

where T: Clone + PartialEq,

Copies the signal, sharing the same inner state.

A Signal is just a raw pointer; copying it is a trivial bitwise copy.