feat: finish two creational design pattern

Author: sqmw

.gitignore

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+# https://dart.dev/guides/libraries/private-files
+# Created by `dart pub`
+.dart_tool/

.idea/.gitignore

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+## 1.0.0
+
+- Initial version.

.idea/libraries/Dart_Packages.xml

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+A sample command-line application with an entrypoint in `bin/`, library code
+in `lib/`, and example unit test in `test/`.

.idea/libraries/Dart_SDK.xml

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+# This file configures the static analysis results for your project (errors,
+# warnings, and lints).
+#
+# This enables the 'recommended' set of lints from `package:lints`.
+# This set helps identify many issues that may lead to problems when running
+# or consuming Dart code, and enforces writing Dart using a single, idiomatic
+# style and format.
+#
+# If you want a smaller set of lints you can change this to specify
+# 'package:lints/core.yaml'. These are just the most critical lints
+# (the recommended set includes the core lints).
+# The core lints are also what is used by pub.dev for scoring packages.
+
+include: package:lints/recommended.yaml
+
+# Uncomment the following section to specify additional rules.
+
+# linter:
+#   rules:
+#     - camel_case_types
+
+# analyzer:
+#   exclude:
+#     - path/to/excluded/files/**
+
+# For more information about the core and recommended set of lints, see
+# https://dart.dev/go/core-lints
+
+# For additional information about configuring this file, see
+# https://dart.dev/guides/language/analysis-options

.idea/misc.xml

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+/// 有两个<接口>
+///   1. 一个是 被工厂生产的 Object 的接口
+///   2. 一个是工厂的 接口
+
+
+/// 被工厂生产的 Object 的 接口
+abstract class Product{
+  void produce();
+}
+
+class ConcreteProductA implements Product{
+  @override
+  void produce() {
+    // TODO: implement produce
+    print('Product A is producing');
+  }
+}
+
+
+class ConcreteProductB implements Product{
+  @override
+  void produce() {
+    // TODO: implement produce
+    print('Product B is producing');
+  }
+}
+
+/// 生产 Object 的工厂的接口
+abstract class ProductFactory{
+  Product createProduct();
+}
+
+class ConcreteProductAFactory implements ProductFactory{
+  @override
+  Product createProduct() {
+    // TODO: implement createProduct
+    return ConcreteProductA();
+  }
+}
+
+class ConcreteProductBFactory implements ProductFactory{
+  @override
+  Product createProduct() {
+    // TODO: implement createProduct
+    return ConcreteProductB();
+  }
+}
+
+void main(){
+  ProductFactory productAFactory = ConcreteProductAFactory();
+  Product productA = productAFactory.createProduct();
+  productA.produce();
+
+  ProductFactory productBFactory = ConcreteProductBFactory();
+  Product productB = productBFactory.createProduct();
+  productB.produce();
+}

.idea/modules.xml

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+/// dart 语言本身的 factory 关键字就是工厂模式的体现
+/// 仅仅一个被生产 Object 的接口
+abstract class Animal {
+  void run();
+}
+
+class Dog implements Animal {
+  @override
+  void run() {
+    // TODO: implement run
+    print("Dog run");
+  }
+}
+
+class Cat implements Animal {
+  @override
+  void run() {
+    // TODO: implement run
+    print('Cat run');
+  }
+}
+/// 在不可以函数编程的编程语言里面使用静态内部类实现
+Animal? animalFactory(String animalName) {
+  if (animalName.toLowerCase() == 'dog') {
+    return Dog();
+  }else if(animalName.toLowerCase() == 'cat'){
+    return Cat();
+  }else{
+    throw Exception("illegal arg");
+  }
+}
+
+void main() {
+  /// 下面两个创建的可以使用
+  ///   1、可以为 null 使用 ?
+  ///   2、强制指定非空 使用 !
+  // 生产猫
+  Animal? cat = animalFactory('cat');
+  // cat run
+  cat?.run();
+
+  // 生产狗
+  Animal dog = animalFactory('dog')!;
+  // dog run
+  dog.run();
+
+  /// 测试不存在的
+  // 测试 error
+  Animal other = animalFactory('other')!;
+  other.run();
+}

CHANGELOG.md

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+import 'package:design_pattern/design_pattern.dart' as design_pattern;
+
+void main(List<String> arguments) {
+  assert(1 != 1 );
+}

README.md

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="WEB_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <excludeFolder url="file://$MODULE_DIR$/.dart_tool" />
+      <excludeFolder url="file://$MODULE_DIR$/.pub" />
+      <excludeFolder url="file://$MODULE_DIR$/build" />
+    </content>
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="Dart SDK" level="project" />
+    <orderEntry type="library" name="Dart Packages" level="project" />
+  </component>
+</module>

analysis_options.yaml

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+int calculate() {
+  return 6 * 7;
+}