Struct leptos::WriteSignal

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pub struct WriteSignal<T>
where T: 'static,
{ /* private fields */ }
Expand description

The setter for a reactive signal.

A signal is a piece of data that may change over time, and notifies other code when it has changed. This is the core primitive of Leptos’s reactive system.

Calling WriteSignal::update will mutate the signal’s value in place, and notify all subscribers that the signal’s value has changed.

WriteSignal implements Fn, such that set_value(new_value) is equivalent to set_value.update(|value| *value = new_value).

WriteSignal is Copy and 'static, so it can very easily moved into closures or copied structs.

§Core Trait Implementations

  • .set() (or calling the setter as a function) sets the signal’s value, and notifies all subscribers that the signal’s value has changed. to subscribe to the signal, and to re-run whenever the value of the signal changes.
  • .update() mutates the signal’s value in place and notifies all subscribers that the signal’s value has changed.

§Examples

let (count, set_count) = create_signal(0);

// ✅ calling the setter sets the value
//    `set_count(1)` on nightly
set_count.set(1);
assert_eq!(count.get(), 1);

// ❌ you could call the getter within the setter
// set_count.set(count.get() + 1);

// ✅ however it's more efficient to use .update() and mutate the value in place
set_count.update(|count: &mut i32| *count += 1);
assert_eq!(count.get(), 2);

Trait Implementations§

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impl<T> Clone for WriteSignal<T>

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

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl<T> Debug for WriteSignal<T>

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

Formats the value using the given formatter. Read more
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impl<T> From<WriteSignal<T>> for SignalSetter<T>

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fn from(value: WriteSignal<T>) -> SignalSetter<T>

Converts to this type from the input type.
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impl<T> Hash for WriteSignal<T>

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fn hash<H>(&self, state: &mut H)
where H: Hasher,

Feeds this value into the given Hasher. Read more
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fn hash_slice<H>(data: &[Self], state: &mut H)
where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher. Read more
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impl<T> PartialEq for WriteSignal<T>

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fn eq(&self, other: &WriteSignal<T>) -> bool

This method tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl<T> SignalDispose for WriteSignal<T>

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fn dispose(self)

Disposes of the signal. This: Read more
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impl<T> SignalSet for WriteSignal<T>

§Examples

let (count, set_count) = create_signal(0);

// notifies subscribers
set_count.update(|n| *n = 1); // it's easier just to call set_count.set(1), though!
assert_eq!(count.get(), 1);

// you can include arbitrary logic in this update function
// also notifies subscribers, even though the value hasn't changed
set_count.update(|n| if *n > 3 { *n += 1 });
assert_eq!(count.get(), 1);
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type Value = T

The value held by the signal.
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fn set(&self, new_value: T)

Sets the signal’s value and notifies subscribers. Read more
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fn try_set(&self, new_value: T) -> Option<T>

Sets the signal’s value and notifies subscribers. Returns None if the signal is still valid, [Some(T)] otherwise. Read more
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impl<T> SignalSetUntracked<T> for WriteSignal<T>
where T: 'static,

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fn set_untracked(&self, new_value: T)

Sets the signal’s value without notifying dependents.
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fn try_set_untracked(&self, new_value: T) -> Option<T>

Attempts to set the signal if it’s still valid. Returns None if the signal was set, [Some(T)] otherwise.
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impl<T> SignalUpdate for WriteSignal<T>

§Examples

let (count, set_count) = create_signal(0);

// notifies subscribers
set_count.update(|n| *n = 1); // it's easier just to call set_count.set(1), though!
assert_eq!(count.get(), 1);

// you can include arbitrary logic in this update function
// also notifies subscribers, even though the value hasn't changed
set_count.update(|n| if *n > 3 { *n += 1 });
assert_eq!(count.get(), 1);
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type Value = T

The value held by the signal.
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fn update(&self, f: impl FnOnce(&mut T))

Applies a function to the current value to mutate it in place and notifies subscribers that the signal has changed. Read more
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fn try_update<O>(&self, f: impl FnOnce(&mut T) -> O) -> Option<O>

Applies a function to the current value to mutate it in place and notifies subscribers that the signal has changed. Returns [Some(O)] if the signal is still valid, None otherwise. Read more
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impl<T> SignalUpdateUntracked<T> for WriteSignal<T>

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fn update_untracked(&self, f: impl FnOnce(&mut T))

Runs the provided closure with a mutable reference to the current value without notifying dependents.
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fn try_update_untracked<O>(&self, f: impl FnOnce(&mut T) -> O) -> Option<O>

Runs the provided closure with a mutable reference to the current value without notifying dependents and returns the value the closure returned.
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impl<T> Copy for WriteSignal<T>

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impl<T> Eq for WriteSignal<T>

Auto Trait Implementations§

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impl<T> RefUnwindSafe for WriteSignal<T>
where T: RefUnwindSafe,

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impl<T> Send for WriteSignal<T>
where T: Send,

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impl<T> Sync for WriteSignal<T>
where T: Sync,

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impl<T> Unpin for WriteSignal<T>
where T: Unpin,

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impl<T> UnwindSafe for WriteSignal<T>
where T: UnwindSafe,

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Checks if this value is equivalent to the given key. Read more
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impl<Q, K> Equivalent<K> for Q
where Q: Eq + ?Sized, K: Borrow<Q> + ?Sized,

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fn equivalent(&self, key: &K) -> bool

Compare self to key and return true if they are equal.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<El> ElementDescriptorBounds for El
where El: Debug,