Struct zng_var::VarModify

pub struct VarModify<'a, T: VarValue> { /* private fields */ }

Represents the current value in a Var::modify handler.

Implementations

impl<'a, T: VarValue> VarModify<'a, T>

pub fn set(&mut self, new_value: T)

Replace the value.

The variable will update if the new value is not equal to the previous after all modify closures apply.

pub fn update(&mut self)

Notify an update, even if the value does not actually change.

pub fn to_mut(&mut self) -> &mut T

Returns a mutable reference for modification.

Note that this clones the current value if this is the first modify closure requesting it.

The variable will update if the new value is not equal to the previous after all modify closures apply.

pub fn tags(&self) -> &[Box<dyn AnyVarValue>]

Custom tags that will be shared with the var hooks if the value updates.

The tags where set by previous modify closures or this one during this update cycle, so tags can also be used to communicate between modify closures.

pub fn push_tag(&mut self, tag: impl AnyVarValue)

Add a custom tag object that will be shared with the var hooks if the value updates.

pub fn push_tags(&mut self, tags: Vec<Box<dyn AnyVarValue>>)

Add all custom tags.

pub fn set_modify_importance(&mut self, importance: usize)

Sets a custom AnyVar::modify_importance value.

Note that the modify info is already automatically set, using a custom value here can easily break all future modify requests for this variable. The importance is set even if the variable does not update (no actual value change or update request).

pub fn new(current_value: &'a T) -> Self

New from current value.

pub fn finish( self, ) -> (bool, Option<T>, bool, Vec<Box<dyn AnyVarValue>>, Option<usize>)

Returns (notify, new_value, update, tags, custom_importance).

Trait Implementations

impl<'a, T: VarValue> AsRef<T> for VarModify<'a, T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'a, T: VarValue> Deref for VarModify<'a, T>

type Target = T

The resulting type after dereferencing.

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

Dereferences the value.