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Reactter

Event Handler Methods

Reactter provides several methods to manage events in a more efficient way. These methods are used to create and manipulate events in a more organized way.

Rt.on

The Rt.on method listens for an event emitted by an instance, allowing the listener to respond whenever the event occurs.

Syntax

void on<T, P>(
  Object? instance,
  Enum eventName,
  Functioon(T instance, P param) callback,
);

Parameters

  • instance: The T instance to listen to.
  • event: The Enum event to listen to.
  • callback : The function to execute when the event is emitted. The function should accept two parameters:
    • instance: The T instance that emitted the event.
    • param: The P parameter passed when the event is emitted.

Example

See the example below to understand how to use the Rt.on method:

 
1
import 'package:flutter/material.dart';
2
import 'package:reactter/reactter.dart';
3
import 'my_dependency.dart';
4


5
void main() {
6
  // Listen to the `myEvent` event of the `MyDependency` before it's created.
7
  Rt.on(
8
    RtDependency<MyDependency>(),
9
    CustomEvent.myEvent,
10
    (instance, param) => print('CustomEvent emitted with param: $param'),
11
  );
12


13
  // Create a new instance of `MyDependency`.
14
  final myDependency = Rt.create(() => MyDependency())!;
15


16
  // Listen to the `didUpdate` event of the `MyDependency` instance.
17
  Rt.on<MyDependency, RtState>(
18
    myDependency,
19
    Lifecycle.didUpdate,
20
    (instance, state) => print('The state updated is: ${state.runtimeType}'),
21
  );
22


23
  // Listen to the `didUpdate` event of the `stateA`.
24
  Rt.on(
25
    myDependency.stateA,
26
    Lifecycle.didUpdate,
27
    (instance, Signal state) => print('stateA updated: ${state.value}'),
28
  );
29


30
  // Listen to the `didUpdate` event of the `stateB`.
31
  Rt.on(
32
    myDependency.stateB,
33
    Lifecycle.didUpdate,
34
    (instance, Signal state) => print('stateB updated: ${state.value}'),
35
  );
35 collapsed lines
36


37
  // Change the value of `stateA` to `10`.
38
  // Print:
39
  //  stateA updated: 10
40
  //  The state updated is: Signal<int>
41
  myDependency.stateA.value = 10;
42


43
  // Change the value of `stateB` to `'Hello World!'`.
44
  // Print:
45
  //  stateB updated: 'Hello World!'
46
  //  The state updated is: Signal<String>
47
  myDependency.stateB.value = 'Hello World!';
48


49
  // Emit the `myEvent` event with the parameter `test`.
50
  // Print:
51
  //  CustomEvent.myEvent emitted with param: test
52
  Rt.emit(myDependency, CustomEvent.myEvent, 'test');
53


54
  // Delete the `MyDependency` instance
55
  Rt.delete<MyDependency>();
56


57
  // Cannot listen to the `didUpdate` event of the `MyDependency` instance
58
  // because it's deleted. This will throw an error.
59
  // myDependency.stateA.value = 20;
60


61
  // Cannot listen to the `myEvent` event using the `MyDependency` instance
62
  // because it's deleted.
63
  Rt.emit(myDependency, CustomEvent.myEvent, 'This is not printed');
64


65
  // Can still emit to the `myEvent` event using the `RtDependency`
66
  // Print:
67
  //  CustomEvent.myEvent emitted with param: 42
68
  Rt.emit(RtDependency<MyDependency>(), CustomEvent.myEvent, 42);
69


70
  runApp(MyApp());
71
}
13 collapsed lines
72


73
class MyApp extends StatelessWidget {
74
  @override
75
  Widget build(BuildContext context) {
76
    return MaterialApp(
77
      home: Material(
78
        child: Center(
79
          child: Text('See the output in the terminal'),
80
        ),
81
      ),
82
    );
83
  }
84
}
1
import 'package:reactter/reactter.dart';
2


3
enum CustomEvent { myEvent }
4


5
class MyDependency {
6
  final stateA = Signal(0);
7
  final stateB = Signal('InitialValue');
8
}

Rt.one

The Rt.one method listens for an event emitted by an instance, but only once. After the event is triggered, the listener is automatically removed.

Syntax

void one<T, P>(
  Object? instance,
  Enum eventName,
  Functioon(T instance, P param) callback,
);

Parameters

  • instance: The T instance to listen to.
  • event: The Enum event to listen to.
  • callback : The function to execute when the event is emitted. The function should accept two parameters:
    • instance: The T instance that emitted the event.
    • param: The P parameter passed when the event is emitted.

Example

See the example below to understand how to use the Rt.one method:

 
1
import 'package:flutter/material.dart';
2
import 'package:reactter/reactter.dart';
3
import 'my_dependency.dart';
4


5
void main() {
6
  // Listen to the `myEvent` event of the `MyDependency` before it's created.
7
  Rt.one(
8
    RtDependency<MyDependency>(),
9
    CustomEvent.myEvent,
10
    (instance, param) => print('CustomEvent emitted with param: $param'),
11
  );
12


13
  // Create a new instance of `MyDependency`.
14
  final myDependency = Rt.create(() => MyDependency())!;
15


16
  // Listen to the `didUpdate` event of the `MyDependency` instance.
17
  Rt.one<MyDependency, RtState>(
18
    myDependency,
19
    Lifecycle.didUpdate,
20
    (instance, state) => print('The state updated is: ${state.runtimeType}'),
21
  );
22


23
  // Listen to the `didUpdate` event of the `stateA`.
24
  Rt.one(
25
    myDependency.stateA,
26
    Lifecycle.didUpdate,
27
    (instance, Signal state) => print('stateA updated: ${state.value}'),
28
  );
29


30
  // Listen to the `didUpdate` event of the `stateB`.
31
  Rt.one(
32
    myDependency.stateB,
33
    Lifecycle.didUpdate,
34
    (instance, Signal state) => print('stateB updated: ${state.value}'),
35
  );
31 collapsed lines
36


37
  // Change the value of `stateA` to `10`.
38
  // Print:
39
  //  stateA updated: 10
40
  // The state updated is: Signal<int>
41
  myDependency.stateA.value = 10;
42


43
  // Change the value of `stateB` to `'Hello World!'`.
44
  // No print for the `didUpdate` event of `MyDependency` instance
45
  // because it's a one-time listener.
46
  // Print:
47
  //  stateB updated: 'Hello World!'
48
  myDependency.stateB.value = 'Hello World!';
49


50
  // Emit the `myEvent` event with the parameter `test`.
51
  // Print:
52
  //  CustomEvent.myEvent emitted with param: test
53
  Rt.emit(myDependency, CustomEvent.myEvent, 'test');
54


55
  // Delete the `MyDependency` instance
56
  Rt.delete<MyDependency>();
57


58
  // Cannot listen to the `didUpdate` event of the `MyDependency` instance
59
  // because it's deleted. This will throw an error.
60
  // myDependency.stateA.value = 20;
61


62
  /// Cannot listen to the `myEvent` event using the `MyDependency` instance
63
  /// because the listener is one-time.
64
  Rt.emit(RtDependency<MyDependency>(), CustomEvent.myEvent, 42);
65


66
  runApp(MyApp());
67
}
13 collapsed lines
68


69
class MyApp extends StatelessWidget {
70
  @override
71
  Widget build(BuildContext context) {
72
    return MaterialApp(
73
      home: Material(
74
        child: Center(
75
          child: Text('See the output in the terminal'),
76
        ),
77
      ),
78
    );
79
  }
80
}
1
import 'package:reactter/reactter.dart';
2


3
enum CustomEvent { myEvent }
4


5
class MyDependency {
6
  final stateA = Signal(0);
7
  final stateB = Signal('InitialValue');
8
}

Rt.emit

The Rt.emit method triggers an event from an instance, notifying all listeners of that event.

Syntax

void emit(
  Object? instance,
  Enum eventName,
  dynamic param,
);

Parameters

  • instance: The instance to emit the event.
  • event: The Enum event to emit.
  • param: The parameter to pass when emitting the event.

Example

See the example below to understand how to use the Rt.emit method:

 
1
import 'package:flutter/material.dart';
2
import 'package:reactter/reactter.dart';
3
import 'my_dependency.dart';
4


5
void main() {
43 collapsed lines
6
  // Listen to the `myEvent` event of the `MyDependency` before it's created.
7
  Rt.on(
8
    RtDependency<MyDependency>(),
9
    CustomEvent.myEvent,
10
    (instance, param) => print('CustomEvent emitted with param: $param'),
11
  );
12


13
  // Create a new instance of `MyDependency`.
14
  final myDependency = Rt.create(() => MyDependency())!;
15


16
  // Listen to the `didUpdate` event of the `MyDependency` instance.
17
  Rt.on<MyDependency, RtState>(
18
    myDependency,
19
    Lifecycle.didUpdate,
20
    (instance, state) => print('The state updated is: ${state.runtimeType}'),
21
  );
22


23
  // Listen to the `didUpdate` event of the `stateA`.
24
  Rt.on(
25
    myDependency.stateA,
26
    Lifecycle.didUpdate,
27
    (instance, Signal state) => print('stateA updated: ${state.value}'),
28
  );
29


30
  // Listen to the `didUpdate` event of the `stateB`.
31
  Rt.on(
32
    myDependency.stateB,
33
    Lifecycle.didUpdate,
34
    (instance, Signal state) => print('stateB updated: ${state.value}'),
35
  );
36


37
  // Change the value of `stateA` to `10`.
38
  // Print:
39
  //  stateA updated: 10
40
  //  The state updated is: Signal<int>
41
  myDependency.stateA.value = 10;
42


43
  // Change the value of `stateB` to `'Hello World!'`.
44
  // Print:
45
  //  stateB updated: 'Hello World!'
46
  //  The state updated is: Signal<String>
47
  myDependency.stateB.value = 'Hello World!';
48


49
  // Emit the `myEvent` event with the parameter `test`.
50
  // Print:
51
  //  CustomEvent.myEvent emitted with param: test
52
  Rt.emit(myDependency, CustomEvent.myEvent, 'test');
8 collapsed lines
53


54
  // Delete the `MyDependency` instance
55
  Rt.delete<MyDependency>();
56


57
  // Cannot listen to the `didUpdate` event of the `MyDependency` instance
58
  // because it's deleted. This will throw an error.
59
  // myDependency.stateA.value = 20;
60


61
  // Cannot listen to the `myEvent` event using the `MyDependency` instance
62
  // because it's deleted.
63
  Rt.emit(myDependency, CustomEvent.myEvent, 'This is not printed');
64


65
  // Can still emit to the `myEvent` event using the `RtDependency`
66
  // Print:
67
  //  CustomEvent.myEvent emitted with param: 42
68
  Rt.emit(RtDependency<MyDependency>(), CustomEvent.myEvent, 42);
2 collapsed lines
69


70
  runApp(MyApp());
71
}
13 collapsed lines
72


73
class MyApp extends StatelessWidget {
74
  @override
75
  Widget build(BuildContext context) {
76
    return MaterialApp(
77
      home: Material(
78
        child: Center(
79
          child: Text('See the output in the terminal'),
80
        ),
81
      ),
82
    );
83
  }
84
}
1
import 'package:reactter/reactter.dart';
2


3
enum CustomEvent { myEvent }
4


5
class MyDependency {
6
  final stateA = Signal(0);
7
  final stateB = Signal('InitialValue');
8
}

Rt.off

The Rt.off method removes a specific event listener from an instance, stopping it from receiving further notifications for that event.

Syntax

void off<T, P>(
  Object? instance,
  Enum eventName,
  Functioon(T instance, P param) callback,
);

Parameters

  • instance: The T instance to stop listening to.
  • event: The Enum event to stop listening to.
    • callback : The function to stop executing the callback. The function should accept two parameters:
    • instance: The T instance that emitted the event.
    • param: The P parameter passed when the event is emitted.

Example

See the example below to understand how to use the Rt.off method:

 
1
import 'package:flutter/material.dart';
2
import 'package:reactter/reactter.dart';
3
import 'my_dependency.dart';
17 collapsed lines
4


5
void onMyEvent(instance, param) {
6
  print('CustomEvent emitted with param: $param');
7
}
8


9
void onDidUpdate(instance, state) {
10
  print('The state updated is: ${state.runtimeType}');
11
}
12


13
void onDidUpdateStateA(instance, Signal state) {
14
  print('stateA updated: ${state.value}');
15
}
16


17
void onDidUpdateStateB(instance, Signal state) {
18
  print('stateB updated: ${state.value}');
19
}
20


21
void main() {
40 collapsed lines
22
  // Listen to the `myEvent` event of the `MyDependency` before it's created.
23
  Rt.on(
24
    RtDependency<MyDependency>(),
25
    CustomEvent.myEvent,
26
    onMyEvent,
27
  );
28


29
  // Create a new instance of `MyDependency`.
30
  final myDependency = Rt.create(() => MyDependency())!;
31


32
  // Listen to the `didUpdate` event of the `MyDependency` instance.
33
  Rt.on<MyDependency, RtState>(
34
    myDependency,
35
    Lifecycle.didUpdate,
36
    onDidUpdate,
37
  );
38


39
  // Listen to the `didUpdate` event of the `stateA`.
40
  Rt.on(myDependency.stateA, Lifecycle.didUpdate, onDidUpdateStateA);
41


42
  // Listen to the `didUpdate` event of the `stateB`.
43
  Rt.on(myDependency.stateB, Lifecycle.didUpdate, onDidUpdateStateB);
44


45
  // Change the value of `stateA` to `10`.
46
  // Print:
47
  //  stateA updated: 10
48
  //  The state updated is: Signal<int>
49
  myDependency.stateA.value = 10;
50


51
  // Change the value of `stateB` to `'Hello World!'`.
52
  // Print:
53
  //  stateB updated: 'Hello World!'
54
  //  The state updated is: Signal<String>
55
  myDependency.stateB.value = 'Hello World!';
56


57
  // Emit the `myEvent` event with the parameter `test`.
58
  // Print:
59
  //  CustomEvent.myEvent emitted with param: test
60
  Rt.emit(myDependency, CustomEvent.myEvent, 'test');
61


62
  // Stop listening to the `myEvent` event of the `MyDependency`
63
  Rt.off(
64
    RtDependency<MyDependency>(),
65
    CustomEvent.myEvent,
66
    onMyEvent,
67
  );
68


69
  // Stop listening to the `didUpdate` event of the `MyDependency` instance
70
  Rt.off(myDependency, Lifecycle.didUpdate, onDidUpdate);
71


72
  // Stop listening to the `didUpdate` event of the `stateA`
73
  Rt.off(myDependency.stateA, Lifecycle.didUpdate, onDidUpdateStateA);
10 collapsed lines
74


75
  // No print for neither `stateA` nor the `MyDependency` instance
76
  // because the listeners are removed
77
  myDependency.stateA.value = 20;
78


79
  // Cannot listen to the `myEvent` event using the `MyDependency` instance
80
  // because the listener is removed
81
  Rt.emit(myDependency, CustomEvent.myEvent, 'This is not printed');
82


83
  runApp(MyApp());
84
}
13 collapsed lines
85


86
class MyApp extends StatelessWidget {
87
  @override
88
  Widget build(BuildContext context) {
89
    return MaterialApp(
90
      home: Material(
91
        child: Center(
92
          child: Text('See the output in the terminal'),
93
        ),
94
      ),
95
    );
96
  }
97
}
1
import 'package:reactter/reactter.dart';
2


3
enum CustomEvent { myEvent }
4


5
class MyDependency {
6
  final stateA = Signal(0);
7
  final stateB = Signal('InitialValue');
8
}

Rt.offAll

The Rt.offAll method removes all event listeners for a specific event from an instance, ensuring no listeners are notified when the event is triggered in the future.

Syntax

void offAll<T>(Object? instance);

Parameters

  • instance: The T instance to stop listening to all events.

Example

See the example below to understand how to use the Rt.offAll method:

 
1
import 'package:flutter/material.dart';
2
import 'package:reactter/reactter.dart';
3
import 'my_dependency.dart';
4


5
void main() {
48 collapsed lines
6
  // Listen to the `myEvent` event of the `MyDependency` before it's created.
7
  Rt.on(
8
    RtDependency<MyDependency>(),
9
    CustomEvent.myEvent,
10
    (instance, param) => print('CustomEvent emitted with param: $param'),
11
  );
12


13
  // Create a new instance of `MyDependency`.
14
  final myDependency = Rt.create(() => MyDependency())!;
15


16
  // Listen to the `didUpdate` event of the `MyDependency` instance.
17
  Rt.on<MyDependency, RtState>(
18
    myDependency,
19
    Lifecycle.didUpdate,
20
    (instance, state) => print('The state updated is: ${state.runtimeType}'),
21
  );
22


23
  // Listen to the `didUpdate` event of the `stateA`.
24
  Rt.on(
25
    myDependency.stateA,
26
    Lifecycle.didUpdate,
27
    (instance, Signal state) => print('stateA updated: ${state.value}'),
28
  );
29


30
  // Listen to the `didUpdate` event of the `stateB`.
31
  Rt.on(
32
    myDependency.stateB,
33
    Lifecycle.didUpdate,
34
    (instance, Signal state) => print('stateB updated: ${state.value}'),
35
  );
36


37
  // Change the value of `stateA` to `10`.
38
  // Print:
39
  //  stateA updated: 10
40
  //  The state updated is: Signal<int>
41
  myDependency.stateA.value = 10;
42


43
  // Change the value of `stateB` to `'Hello World!'`.
44
  // Print:
45
  //  stateB updated: 'Hello World!'
46
  //  The state updated is: Signal<String>
47
  myDependency.stateB.value = 'Hello World!';
48


49
  // Emit the `myEvent` event with the parameter `test`.
50
  // Print:
51
  //  CustomEvent.myEvent emitted with param: test
52
  Rt.emit(myDependency, CustomEvent.myEvent, 'test');
53


54
  // Remove all event listeners of `stateA`.
55
  Rt.offAll(myDependency.stateA);
56


57
  // Remove all event listeners of `myDependency`,
58
  // including the generic listeners (using `RtDependency`).
59
  Rt.offAll(myDependency, true);
16 collapsed lines
60


61
  // No print for neither `stateA` nor the `MyDependency` instance
62
  // because the listeners are removed
63
  myDependency.stateA.value = 20;
64


65
  // Change the value of `stateB` to `Hey you!'`.
66
  // Only print for the `didUpdate` event of `stateB`.
67
  // Print:
68
  //  stateB updated: 'Hey you!'
69
  myDependency.stateB.value = 'Hey you!';
70


71
  // Cannot listen to the `myEvent` event using the `MyDependency` instance
72
  // because the listeners are removed.
73
  Rt.emit(myDependency, CustomEvent.myEvent, 'This is not printed');
74


75
  runApp(MyApp());
76
}
13 collapsed lines
77


78
class MyApp extends StatelessWidget {
79
  @override
80
  Widget build(BuildContext context) {
81
    return MaterialApp(
82
      home: Material(
83
        child: Center(
84
          child: Text('See the output in the terminal'),
85
        ),
86
      ),
87
    );
88
  }
89
}
1
import 'package:reactter/reactter.dart';
2


3
enum CustomEvent { myEvent }
4


5
class MyDependency {
6
  final stateA = Signal(0);
7
  final stateB = Signal('InitialValue');
8
}