MetaCell<T> class
A cell that points to another cell.
This cell points to another, which the value of this cell is the value of the cell it points to and the observers of this cell are notified when the value of the cell it points to changes.
The pointed to cell is set after construction and can be changed multiple times. NOTE: The observers of this cell are not notified when the pointed to cell changes.
If value is accessed before the cell, to which this cell points to, is set an EmptyMetaCellError exception is thrown. Note, also this cell must have at least one observer before setting the cell to which it points to.
Usage:
final a = MutableCell(0);
final b = MutableCell(10);
final meta = MetaCell<int>();
ValueCell.watch(() => print(meta()));
// `meta` now points to `a`
meta.setCell(a);
print(meta.value); // Prints: 0
// The following causes the watch function defiend above
// to be called
a.value = 1; // Prints: 1
a.value = 2; // Prints: 2
// `meta` now points to `b`
meta.setCell(b);
b.value = 11; // Prints: 11
b.value = 12; // Prints: 12
- Inheritance
-
- Object
- ValueCell<
T> - StatefulCell<
T> - MetaCell
- Implementers
- Available extensions
- ActionCellEffectExtension
- ActionCellExtension
- ActionMetaCellExtension
- BoolCellExtension
- BoolValueChangeExtension
- CellHolderExtension
- ComputeArgumentsTracker
- ComputeExtension
- DelayCellExtension
- DurationCellExtension
- EffectCellExtension
- ErrorCellExtension
- IterableCellExtension
- ListCellExtension
- MapCellExtension
- MaybeCellExtension
- MetaCellExtension
- NullCheckExtension
- NumericExtension
- PeekCellExtension
- PrevValueCellExtension
- SetCellExtension
- StoreCellExtension
- TransformExtension
- ValueChangeExtension
- WaitCellExtension
Constructors
- MetaCell({dynamic key})
- Create a cell that points to another cell.
Properties
- equalityCellFactory → EqualityCellFactory
-
Return a factory for creating equality and inequality comparison cells.
no setterinherited
- hashCode → int
-
The hash code for this object.
no setterinherited
- key ↔ dynamic
-
Key which uniquely identifies the cell
latefinalinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
-
state
→ CellState<
StatefulCell> ? -
The current state of the cell, or null if the cell is inactive.
no setterinherited
- value → T
-
The cell's value
no setteroverride
Methods
-
addObserver(
CellObserver observer) → void -
Register an observer of the cell to be called when the cell's value changes.
inherited
-
call(
) → T -
Retrieve the value of the cell.
inherited
-
createState(
) → CellState< StatefulCell> -
Create the CellState for this cell.
override
-
eq<
U> (ValueCell< U> other) → ValueCell<bool> -
Returns a new ValueCell which compares the value of this cell to another cell for equality.
inherited
-
inject(
ValueCell< T> cell) → void - Alias of setCell.
-
neq<
U> (ValueCell< U> other) → ValueCell<bool> -
Returns a new ValueCell which compares the value of this cell to another cell for inequality.
inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
observe(
) → void -
Track this cell as an argument of the current compute/watch function.
inherited
-
removeObserver(
CellObserver observer) → void -
Remove an observer that was previously registered with addObserver.
inherited
-
setCell(
ValueCell< T> cell) → void - Set the cell to which this cell points to.
-
toString(
) → String -
A string representation of this object.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited
Static Methods
-
action(
{dynamic key}) → ActionMetaCell - Create a MetaCell that points to an ActionCell.
-
mutable<
T> ({dynamic key}) → MutableMetaCell< T> - Create a MetaCell that points to a MutableCell.