Struct Children 

pub struct Children(/* private fields */);

A component’s markup children, not yet built.

Slots is the list a call site already made; this is the recipe for making it. The difference is the whole of what a compound component needs, and it comes from one fact about how a tree is assembled here: a child is an argument, so it is constructed before the parent it is passed to. A Select.Item that wanted to know which select it belongs to, what is currently chosen, or what to call when it is picked, was asking a question about something that did not exist yet.

Handed the recipe instead, the parent builds its context first and then runs the recipe inside it, so a child reaches the parent through use_context rather than through props threaded down by hand. The recipe is Fn, not FnOnce, for a second reason that is not theoretical: a dropdown rebuilds its rows every time the panel opens, so the children have to be makeable more than once.

Implementations

impl Children

pub fn new(build: impl Fn() -> Result<Slots, LayoutError> + 'static) -> Self

pub fn build_with<T: Any + 'static>( &self, context: T, ) -> Result<Slots, LayoutError>

Builds the children with context visible to every one of them, and to anything they build in turn.

The scope is nested, so a select inside a select’s own row shadows the outer one rather than colliding with it, and it closes when this returns — a widget built afterwards sees nothing.

pub fn build(&self) -> Result<Slots, LayoutError>

Builds the children with no context of their own, for a component that has nothing to tell them.

Trait Implementations

impl Clone for Children

fn clone(&self) -> Children

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Default for Children

fn default() -> Self

Returns the “default value” for a type.

impl From<Slots> for Children

fn from(slots: Slots) -> Self

For a caller holding children it already built — a test, or a component forwarding what it was given. The recipe hands them out once and is empty on any later call, since a built widget cannot be made twice.