undone 0.0.4

A little undo-redo library. Not a song about sweaters.

Undone

A little undo-redo library.

Usage

Build an Action from Functions

// Actions bind a 'Do' functon and an 'Undo' function together with arguments.
Do _increment = (a) => ++a['value'];
Undo _decrement = (a, _) => --a['value'];  
var map = { 'value' : 42 }; 
var increment = new Action(map, _increment, _decrement);

Define a Custom Action Type

// Use custom actions when you want your own type.
class Power2 extends Action {  
  static _square(a) => a['value'] = a['value'] * a['value'];  
  static _squareRoot(a, r) => a['value'] = math.sqrt(a['value']);  
  Power2(map): super(map, _square, _squareRoot);  
}

Schedule an Action

// Call your action, and listen for the result (if you want) - its easy!
increment().then((result) => print('$result')); // prints '43'

Schedule a Transaction

var square = new Power2(map);
  
transact(() {
    increment();
    square();
}).then((_) => print('${map["value"]}')); // prints '1936'

Undo and Redo

// Bind undo / redo to keyboard events.
document.onKeyUp.listen((e) {    
  if (e.ctrlKey) {
    if (e.keyCode == KeyCode.Z)           undo();
    else if (e.keyCode == KeyCode.Y)      redo();
  }
});

Run the Examples

The code above can be found here. For more fun, try to nudge a box around a canvas - its undoable!

Undone uses the MIT license as described in the LICENSE file, and follows semantic versioning.