ZenithSelector<T, R> class

A widget that rebuilds only when a selected portion of a ZenithNode's value changes.

Unlike ZenithBuilder which rebuilds when any read node changes, ZenithSelector extracts a derived value via selector and only rebuilds when that derived value is different from the previous one (compared with ==).

This is essential for performance in list-heavy UIs where a single node holds a large collection but individual widgets only care about one element:

ZenithSelector<List<Item>, String>(
  node: itemsNode,
  selector: (items) => items[index].name,
  builder: (context, name) => Text(name),
)
Inheritance

Constructors

ZenithSelector({Key? key, required ZenithNode<T> node, required R selector(T value), required Widget builder(BuildContext context, R selected)})
Creates a ZenithSelector.
const

Properties

builder → Widget Function(BuildContext context, R selected)
Builds the widget subtree using the selected value.
final
hashCode → int
The hash code for this object.
no setterinherited
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
node → ZenithNode<T>
The source node to observe.
final
runtimeType → Type
A representation of the runtime type of the object.
no setterinherited
selector → R Function(T value)
Extracts the derived value from the node's current value.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<ZenithSelector<T, R>>
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
inherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a nonexistent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

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