Consumer<T> class

A widget whose content stays synced with a Watchable.

Given a Watchable<T> and a builder which builds widgets from concrete values of T, this class will automatically register itself as a listener of the Watchable and call the builder with updated values when the value changes.

Performance optimizations

If your builder function contains a subtree that does not depend on the value of the Watchable, it's more efficient to build that subtree once instead of rebuilding it on every animation tick.

If you pass the pre-built subtree as the child parameter, the Consumer will pass it back to your builder function so that you can incorporate it into your build.

Using this pre-built child is entirely optional, but can improve performance significantly in some cases and is therefore a good practice.

Inheritance

• Object
• DiagnosticableTree
• Widget
• StatelessWidget
• Consumer

Constructors

Consumer({Key? key, required Watchable<T> watchable, required ValueWidgetBuilder<T> builder, Widget? child})

Creates a Consumer.

const

Properties

builder → ValueWidgetBuilder<T>

A ValueWidgetBuilder which builds a widget depending on the watchable's current state.

final

child → Widget?

A watchable-independent widget which is passed back to the builder.

final

hashCode → int

The hash code for this object.

no setter, inherited

key → Key?

Controls how one widget replaces another widget in the tree.

final, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

watchable → Watchable<T>

The Watchable whose state you depend on, in order to build. This can be a StateRef, a Computed, but you can also use it with the result of the select method.

final

Methods

build(BuildContext context) → Widget

Describes the part of the user interface represented by this widget.

override

createElement() → StatelessElement

Creates a StatelessElement to manage this widget's location in the tree.

inherited

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}) → 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