Struct ElementRef 

pub struct ElementRef<T: ObjectType>(/* private fields */);

A reference to an element that the holder does not own: the value type of properties such as a placement target, the target of a label or the element an adorner adorns.

Such a property points sideways or up the tree — often at an ancestor of the element it is set on — so holding the element strongly would make the two keep each other alive. An ElementRef holds it weakly and compares by identity. Classes expose these properties with getters that return Option<Ref<T>> and setters that take impl Into<Nullable<T>>; untyped access and bindings convert to and from Ref<T> (see ValueTypes::register_element_ref).

When the referenced element is dropped the reference reads as nothing; no change notification is raised for that.

Implementations

impl<T: ObjectType> ElementRef<T>

pub fn new<U: ObjectType + Upcast<T>>(element: &Ref<U>) -> Self

Creates a reference to element.

pub fn of(element: &Ref<T>) -> Self

Creates a reference to an element of exactly class T.

pub fn from_nullable(element: Option<Ref<T>>) -> Option<Self>

The property value for an optional element.

pub fn get(&self) -> Option<Ref<T>>

The referenced element, if it is still alive.

pub fn resolve(value: &Option<Self>) -> Option<Ref<T>>

The element referenced by a property value.

pub fn points_to<U: ObjectType>(&self, element: &Ref<U>) -> bool

Whether the reference points at element.

Trait Implementations

impl<T: ObjectType> Clone for ElementRef<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<T: ObjectType> Debug for ElementRef<T>

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

Formats the value using the given formatter.

impl<T: ObjectType + Upcast<U>, U: ObjectType> From<&Ref<T>> for ElementRef<U>

fn from(value: &Ref<T>) -> Self

Converts to this type from the input type.

impl<T: ObjectType> PartialEq for ElementRef<T>

Identity: two references are equal when they point at the same element, whether or not it is still alive.

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.