Merge pull request #40 from ilopX/add-abstract-factory-pattern

Add Conceptual Gui Factory - abstract factory pattern.

Author: ilopX

CHANGELOG.md

@@ -1,3 +1,6 @@
+## 0.19.0
+- Add "Conceptual Gui Factory" example.
+
 ## 0.18.0
 - Add Memento Editor.
 

README.md

@@ -4,7 +4,7 @@ It contains **Dart** examples for all classic **GoF** design patterns.
 
 # Implementation checklist:
 - [ ] **Creation**
-    - [ ] **Abstract Factory**
+    - [ ] **Abstract Factory** [[Conceptual Gui Factory](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/abstract_factory/conceptual_gui_factory)]
     - [x] **Builder** - [[Color Text Format](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/builder/color_text_format)]
     - [ ] **Factory Method**
     - [x] **Prototype** - [[Shapes](https://github.com/RefactoringGuru/design-patterns-dart/tree/main/patterns/prototype/shapes)] 

patterns/abstract_factory/conceptual_gui_factory/README.md

@@ -0,0 +1,38 @@
+# Abstract Factory pattern
+Abstract Factory is a creational design pattern that lets you produce families of related objects 
+without specifying their concrete classes.
+
+Tutorial: [here](https://refactoring.guru/design-patterns/abstract-factory).
+
+### About example.
+This the very conceptual example rewrite from original source code [java example](https://github.com/RefactoringGuru/design-patterns-java/tree/main/src/refactoring_guru/abstract_factory/example)
+
+### Diagram:
+![image](https://user-images.githubusercontent.com/8049534/165987890-e64db9a3-4865-411c-a5c0-16da21043159.png)
+
+### Client code:
+```dart
+void main() {
+  final guiFactory = GUIFactory();
+  final app = Application(guiFactory);
+  app.paint();
+}
+
+abstract class GUIFactory {
+  factory GUIFactory() {
+    if (Platform.isMacOS) {
+      return MacOSFactory();
+    } else {
+      return WindowsFactory();
+    }
+  }
+  
+  /*...*/
+}
+```
+
+### Output:
+```
+You have created WindowsButton.
+You have created WindowsCheckbox.
+```

patterns/abstract_factory/conceptual_gui_factory/app/application.dart

@@ -0,0 +1,18 @@
+import '../button/button.dart';
+import '../checkbox/checkbox.dart';
+import '../factories/gui_factory.dart';
+
+class Application {
+  late Button _button;
+  late Checkbox _checkbox;
+
+  Application(GUIFactory factory) {
+    _button = factory.createButton();
+    _checkbox = factory.createCheckbox();
+  }
+
+  void paint() {
+    _button.paint();
+    _checkbox.paint();
+  }
+}

patterns/abstract_factory/conceptual_gui_factory/button/button.dart

@@ -0,0 +1,3 @@
+abstract class Button {
+  void paint();
+}

patterns/abstract_factory/conceptual_gui_factory/button/mac_os_button.dart

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+import 'button.dart';
+
+class MacOSButton implements Button {
+  @override
+  void paint() {
+    print('You have created MacOSButton.');
+  }
+}

patterns/abstract_factory/conceptual_gui_factory/button/windows_button.dart

@@ -0,0 +1,8 @@
+import 'button.dart';
+
+class WindowsButton implements Button {
+  @override
+  void paint() {
+    print('You have created WindowsButton.');
+  }
+}

patterns/abstract_factory/conceptual_gui_factory/checkbox/checkbox.dart

@@ -0,0 +1,3 @@
+abstract class Checkbox {
+  void paint();
+}

patterns/abstract_factory/conceptual_gui_factory/checkbox/mac_os_checkbox.dart

@@ -0,0 +1,8 @@
+import 'checkbox.dart';
+
+class MacOSCheckbox implements Checkbox {
+  @override
+  void paint() {
+    print('You have created MacOSCheckbox.');
+  }
+}

patterns/abstract_factory/conceptual_gui_factory/checkbox/windows_checkbox.dart

@@ -0,0 +1,8 @@
+import 'checkbox.dart';
+
+class WindowsCheckbox implements Checkbox {
+  @override
+  void paint() {
+    print('You have created WindowsCheckbox.');
+  }
+}