Selector<A, S> class

An equivalent to Consumer that can filter updates by selecting a limited amount of values and prevent rebuild if they don't change.

Selector will obtain a value using Provider.of, then pass that value to selector. That selector callback is then tasked to return an object that contains only the information needed for builder to complete.

By default, Selector determines if builder needs to be called again by comparing the previous and new result of selector using DeepCollectionEquality from the package collection.

This behavior can be overridden by passing a custom shouldRebuild callback.

NOTE: The selected value must be immutable, or otherwise Selector may think nothing changed and not call builder again.

As such, it selector should return either a collection (List/Map/Set/Iterable) or a class that override ==.

To select multiple values without having to write a class that implements ==, the easiest solution is to use a "Tuple" from tuple:

Selector<Foo, Tuple2<Bar, Baz>>(
  selector: (_, foo) => Tuple2(foo.bar, foo.baz),
  builder: (_, data, __) sync* {
    yield Text('${data.item1}  ${data.item2}');
  }
)

In that example, builder will be called again only if foo.bar or foo.baz changes.

For generic usage information, see Consumer.

Inheritance

Constructors

Selector({Key? key, required ValueComponentBuilder<S> builder, required S selector(BuildContext, A), ShouldRebuild<S>? shouldRebuild, Component? child})
An equivalent to Consumer that can filter updates by selecting a limited amount of values and prevent rebuild if they don't change.

Properties

builder → ValueComponentBuilder<S>
A function that builds a component tree from child and the last result of selector.
finalinherited
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one component replaces another component in the tree.
finalinherited
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
selector → S Function(BuildContext)
A function that obtains some InheritedComponent and map their content into a new object with only a limited number of properties.
finalinherited

Methods

createElement() → SingleChildStatefulElement
Creates a StatefulElement to manage this component's location in the tree.
inherited
createState() → _Selector0State<S>
Creates the mutable state for this component at a given location in the tree.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toString() → String
A string representation of this object.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
inherited