Struct zng::widget::WidgetFn

pub struct WidgetFn<D>(/* private fields */)
where
    D: ?Sized;

Boxed shared closure that generates a widget for a given data.

You can also use the wgt_fn! macro do instantiate.

See presenter for a way to quickly use the widget function in the UI.

Implementations

impl<D> WidgetFn<D>

pub fn new<U>(func: impl Fn(D) -> U + Send + Sync + 'static) -> WidgetFn<D>

where U: UiNode,

New from a closure that generates a node from data.

pub const fn nil() -> WidgetFn<D>

Function that always produces the NilUiNode.

No heap allocation happens to create this value.

pub fn is_nil(&self) -> bool

If this is the nil function.

If true the function always generates a node that is UiNode::is_nil, if false the function may still return a nil node some of the time.

See call_checked for more details.

pub fn call(&self, data: D) -> Box<dyn UiNodeBoxed>

Calls the function with data argument.

Note that you can call the widget function directly where D: 'static:

fn foo(func: &WidgetFn<bool>) {
    let a = func.call(true);
    let b = func(true);
}

In the example above a and b are both calls to the widget function.

pub fn call_checked(&self, data: D) -> Option<Box<dyn UiNodeBoxed>>

Calls the function with data argument and only returns a node if is not nil.

Returns None if is_nil or UiNode::is_nil.

pub fn singleton(widget: impl UiNode) -> WidgetFn<D>

New widget function that returns the same widget for every call.

The widget is wrapped in an ArcNode and every function call returns an ArcNode::take_on_init node. Note that take_on_init is not always the widget on init as it needs to wait for it to deinit first if it is already in use, this could have an effect if the widget function caller always expects a full widget.

pub fn downgrade(&self) -> WeakWidgetFn<D>

Creates a WeakWidgetFn<D> reference to this function.

Trait Implementations

impl<D> Clone for WidgetFn<D>

fn clone(&self) -> WidgetFn<D>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<D> Debug for WidgetFn<D>

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

Formats the value using the given formatter.

impl<D> Default for WidgetFn<D>

fn default() -> WidgetFn<D>

nil.

impl<D> Deref for WidgetFn<D>

where D: 'static,

type Target = dyn Fn(D) -> Box<dyn UiNodeBoxed>

The resulting type after dereferencing.

fn deref(&self) -> &<WidgetFn<D> as Deref>::Target

Dereferences the value.

impl<D> PartialEq for WidgetFn<D>

fn eq(&self, other: &WidgetFn<D>) -> bool

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.