Merge pull request #63 from ilopX/add-conceptual-mediator-pattern

Add conceptual mediator pattern.

Author: ilopX

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.26.0
+- Add conceptual mediator pattern.
+
 ## 0.25.0
 - Add conceptual state pattern: Three State.
 

README.md

@@ -14,10 +14,10 @@ It contains **Dart** examples for all classic **GoF** design patterns.
     - [x] **Command** - [[Text Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/command/text_editor)] 
     - [ ] Interpreter
     - [ ] **Iterator**
-    - [ ] **Mediator**
+    - [x] **Mediator** [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/mediator/conceptual)]
     - [x] **Memento** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/memento/conceptual)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) Memento Editor](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/memento/memento_editor)] 
     - [x] **Observer** - [[Open-Close Editor Events](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/open_close_editor_events)] [[AppObserver](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/app_observer)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) Subscriber Flutter Widget](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/observer/subscriber_flutter_widget)]
-    - [x] **State** - [[Three State](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/state/three_state)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) State Manipulator](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/state/manipulator_state)]
+    - [x] **State** - [[Conceptual](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/state/three_state)] [[![16x16](https://user-images.githubusercontent.com/8049534/171852337-57db0faf-1f5e-489a-a79a-22ed4f47b4ed.png) State Manipulator](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/state/manipulator_state)]
     - [ ] **Template Method**
     - [X] **Visitor**  [[Shape XML Exporter](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/visitor/shapes_exporter)]
     - [X] **Strategy** [[Reservation Cargo Spaces](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/strategy/reservation_cargo_spaces)]

patterns/mediator/conceptual/README.md

@@ -0,0 +1,37 @@
+# Mediator Pattern
+Mediator is a behavioral design pattern that lets you reduce chaotic dependencies between objects. 
+The pattern restricts direct communications between the objects and forces them to collaborate only 
+via a mediator object.
+
+Tutorial: [here](https://refactoring.guru/design-patterns/mediator).
+
+## Conceptual diagram:
+![image](https://user-images.githubusercontent.com/8049534/173237874-971dd4e7-2e74-4cac-bcea-77b88255adad.png)
+
+### Client code:
+```dart
+void main() {
+  final component1 = Component1();
+  final component2 = Component2();
+
+  ConcreteMediator(component1, component2);
+
+  component1.doOne();
+  print('');
+  component2.doTwo();
+}
+```
+
+### Output:
+```
+call Component1.doOne()
+ConcreteMediator.notify(event: "doOne")
+ConcreteMediator.reactComponentOne()
+use component2.name = "Two"
+
+call Component2.doTwo()
+ConcreteMediator.notify(event: "doTwo")
+ConcreteMediator.reactComponentTwo()
+use component1.sate = "Cmp1"
+```
+

patterns/mediator/conceptual/components/component1.dart

@@ -0,0 +1,10 @@
+import '../pattern/mediator.dart';
+
+class Component1 extends Component {
+  final sate = 'Cmp1';
+
+  void doOne() {
+    print('call Component1.doOne()');
+    mediator?.notify(this, 'doOne');
+  }
+}

patterns/mediator/conceptual/components/component2.dart

@@ -0,0 +1,10 @@
+import '../pattern/mediator.dart';
+
+class Component2 extends Component {
+  final name = 'Two';
+
+  void doTwo() {
+    print('call Component2.doTwo()');
+    mediator?.notify(this, 'doTwo');
+  }
+}

patterns/mediator/conceptual/concrete_mediator/concrete_mediator.dart

@@ -0,0 +1,34 @@
+import '../components/component1.dart';
+import '../components/component2.dart';
+import '../pattern/mediator.dart';
+
+class ConcreteMediator extends Mediator {
+  final Component1 component1;
+  final Component2 component2;
+
+  ConcreteMediator(this.component1, this.component2) {
+    applyThisMediator(component1);
+    applyThisMediator(component2);
+  }
+
+  @override
+  void notify(Component component, String event) {
+    print('ConcreteMediator.notify(event: "$event")');
+
+    if (component == component1) {
+      reactComponentOne();
+    } else if (component == component2) {
+      reactComponentTwo();
+    }
+  }
+
+  void reactComponentOne() {
+    print('ConcreteMediator.reactComponentOne()');
+    print('use component2.name = "${component2.name}"');
+  }
+
+  void reactComponentTwo() {
+    print('ConcreteMediator.reactComponentTwo()');
+    print('use component1.sate = "${component1.sate}"');
+  }
+}

patterns/mediator/conceptual/main.dart

@@ -0,0 +1,14 @@
+import 'components/component1.dart';
+import 'components/component2.dart';
+import 'concrete_mediator/concrete_mediator.dart';
+
+void main() {
+  final component1 = Component1();
+  final component2 = Component2();
+
+  ConcreteMediator(component1, component2);
+
+  component1.doOne();
+  print('');
+  component2.doTwo();
+}

patterns/mediator/conceptual/pattern/component.dart

@@ -0,0 +1,7 @@
+part of mediator;
+
+class Component {
+  get mediator => _mediator;
+
+  Mediator? _mediator;
+}

patterns/mediator/conceptual/pattern/mediator.dart

@@ -0,0 +1,11 @@
+library mediator;
+
+part 'component.dart';
+
+abstract class Mediator {
+  void notify(Component component, String event);
+
+  void applyThisMediator(Component component) {
+    component._mediator = this;
+  }
+}

pubspec.yaml

@@ -1,6 +1,6 @@
 name: design_patterns_dart
 description: Dart examples for all classic GoF design patterns.
-version: 0.25.0
+version: 0.26.0
 homepage: https://refactoring.guru/design-patterns
 repository: https://github.com/RefactoringGuru/design-patterns-dart
 issue_tracker: https://github.com/RefactoringGuru/design-patterns-dart/issue