Container hierarchy support

angel_container/CHANGELOG.md

@@ -0,0 +1,5 @@
+# 1.0.0-alpha.1
+* Allow omission of the first argument of `Container.make`, to use
+a generic type argument instead.
+* `singleton` -> `registerSingleton`
+* Add `createChild`, and support hierarchical containers.

angel_container/example/main.dart

@@ -0,0 +1,55 @@
+import 'package:angel_container/angel_container.dart';
+import 'package:angel_container/mirrors.dart';
+
+void main() {
+  // Create a container instance.
+  var container = new Container(MirrorsReflector());
+
+  // Register a singleton.
+  container.registerSingleton<Engine>(Engine(40));
+
+  // Register a factory that creates a truck.
+  container.registerFactory<Truck>((container) {
+    return _TruckImpl(container.make<Engine>());
+  });
+
+  // Use `make` to create an instance.
+  var truck = container.make<Truck>();
+
+  // Should print: 'Vroom! I have 40 horsepower in my engine.'
+  truck.drive();
+
+  // We can make a child container with its own factory.
+  var childContainer = container.createChild();
+
+  childContainer.registerFactory<Truck>((container) {
+    return _TruckImpl(Engine(5666));
+  });
+
+  // Make a truck with 5666 HP.
+  childContainer.make<Truck>().drive();
+
+  // However, calling `make<Engine>` will return the Engine singleton we created above.
+  print(childContainer.make<Engine>().horsePower);
+}
+
+abstract class Truck {
+  void drive();
+}
+
+class Engine {
+  final int horsePower;
+
+  Engine(this.horsePower);
+}
+
+class _TruckImpl implements Truck {
+  final Engine engine;
+
+  _TruckImpl(this.engine);
+
+  @override
+  void drive() {
+    print('Vroom! I have ${engine.horsePower} horsepower in my engine.');
+  }
+}

angel_container/lib/src/container.dart

@@ -4,49 +4,98 @@ import 'reflector.dart';
 class Container {
   final Reflector reflector;
   final Map<Type, dynamic> _singletons = {};
+  final Map<Type, dynamic Function(Container)> _factories = {};
+  final Container _parent;
 
-  Container(this.reflector);
+  Container(this.reflector) : _parent = null;
 
-  T make<T>(Type type) {
-    if (_singletons.containsKey(type)) {
-      return _singletons[type] as T;
-    } else {
-      var reflectedType = reflector.reflectType(type);
-      var positional = [];
-      var named = <String, dynamic>{};
+  Container._child(this._parent) : reflector = _parent.reflector;
 
-      if (reflectedType is ReflectedClass) {
-        bool isDefault(String name) {
-          return name.isEmpty || name == reflectedType.name;
-        }
+  bool get isRoot => _parent == null;
 
-        var constructor = reflectedType.constructors.firstWhere(
-            (c) => isDefault(c.name),
-            orElse: () => throw new ReflectionException(
-                '${reflectedType.name} has no default constructor, and therefore cannot be instantiated.'));
+  /// Creates a child [Container] that can define its own singletons and factories.
+  ///
+  /// Use this to create children of a global "scope."
+  Container createChild() {
+    return new Container._child(this);
+  }
 
-        for (var param in constructor.parameters) {
-          var value = make(param.type.reflectedType);
+  /// Instantiates an instance of [T].
+  ///
+  /// In contexts where a static generic type cannot be used, use
+  /// the [type] argument, instead of [T].
+  T make<T>([Type type]) {
+    type ??= T;
 
-          if (param.isNamed) {
-            named[param.name] = value;
-          } else {
-            positional.add(value);
-          }
-        }
+    // Find a singleton, if any.
+    var search = this;
 
-        return reflectedType.newInstance(
-            isDefault(constructor.name) ? '' : constructor.name,
-            positional,
-            named, []);
+    while (search != null) {
+      if (search._singletons.containsKey(type)) {
+        return search._singletons[type] as T;
       } else {
-        throw new ReflectionException(
-            '$type is not a class, and therefore cannot be instantiated.');
+        search = search._parent;
       }
     }
+
+    // Find a factory, if any.
+    search = this;
+
+    while (search != null) {
+      if (search._factories.containsKey(type)) {
+        return search._factories[type](this) as T;
+      } else {
+        search = search._parent;
+      }
+    }
+
+    var reflectedType = reflector.reflectType(type);
+    var positional = [];
+    var named = <String, dynamic>{};
+
+    if (reflectedType is ReflectedClass) {
+      bool isDefault(String name) {
+        return name.isEmpty || name == reflectedType.name;
+      }
+
+      var constructor = reflectedType.constructors.firstWhere(
+          (c) => isDefault(c.name),
+          orElse: () => throw new ReflectionException(
+              '${reflectedType.name} has no default constructor, and therefore cannot be instantiated.'));
+
+      for (var param in constructor.parameters) {
+        var value = make(param.type.reflectedType);
+
+        if (param.isNamed) {
+          named[param.name] = value;
+        } else {
+          positional.add(value);
+        }
+      }
+
+      return reflectedType.newInstance(
+          isDefault(constructor.name) ? '' : constructor.name,
+          positional,
+          named, []);
+    } else {
+      throw new ReflectionException(
+          '$type is not a class, and therefore cannot be instantiated.');
+    }
   }
 
-  void singleton(Object object, {Type as}) {
+  void registerFactory<T>(T Function(Container) f, {Type as}) {
+    as ??= T;
+
+    if (_factories.containsKey(as)) {
+      throw new StateError('This container already has a factory for $as.');
+    }
+
+    _factories[as] = f;
+  }
+
+  void registerSingleton<T>(T object, {Type as}) {
+    as ??= T == dynamic ? as : T;
+
     if (_singletons.containsKey(as ?? object.runtimeType)) {
       throw new StateError(
           'This container already has a singleton for ${as ?? object.runtimeType}.');

angel_container/pubspec.yaml

@@ -1,7 +1,7 @@
 name: angel_container
 version: 1.0.0-alpha
 author: Tobe O <thosakwe@gmail.com>
-description: "A better IoC container for Angel, ultimately allowing Angel to be used without dart:mirrors."
+description: "A better IoC container and dependency injector for Angel, ultimately allowing Angel to be used without dart:mirrors."
 homepage: https://github.com/angel-dart/container.git
 environment:
   sdk: ">=1.8.0 <3.0.0"

angel_container/test/common.dart

@@ -7,20 +7,24 @@ void testReflector(Reflector reflector) {
 
   setUp(() {
     container = new Container(reflector);
-    container.singleton(blaziken);
+    container.registerSingleton(blaziken);
   });
 
   test('make on singleton type returns singleton', () {
     expect(container.make(Pokemon), blaziken);
   });
 
+  test('make with generic returns same as make with explicit type', () {
+    expect(container.make<Pokemon>(), blaziken);
+  });
+
   test('make on aliased singleton returns singleton', () {
-    container.singleton(blaziken, as: StateError);
+    container.registerSingleton(blaziken, as: StateError);
     expect(container.make(StateError), blaziken);
   });
 
   test('constructor injects singleton', () {
-    var lower = container.make(LowerPokemon) as LowerPokemon;
+    var lower = container.make<LowerPokemon>();
     expect(lower.lowercaseName, blaziken.name.toLowerCase());
   });