refactor(injector): change toFactory to use reflector to construct dependencies

Author: vsavkin

modules/di/src/binding.js

@@ -1,4 +1,4 @@
-import {FIELD, Type, bool} from 'facade/lang';
+import {FIELD, Type, bool, isBlank} from 'facade/lang';
 import {List, MapWrapper, ListWrapper} from 'facade/collection';
 import {reflector} from './reflector';
 import {Key} from './key';
@@ -13,6 +13,7 @@ export class Dependency {
     this.lazy = lazy;
   }
 }
+
 export class Binding {
   constructor(key:Key, factory:Function, dependencies:List, providedAsFuture:bool) {
     this.key = key;
@@ -49,25 +50,27 @@ export class BindingBuilder {
     );
   }
 
-  toFactory(dependencies:List, factoryFunction:Function):Binding {
+  toFactory(factoryFunction:Function, {dependencies=null}={}):Binding {
     return new Binding(
       Key.get(this.token),
       reflector.convertToFactory(factoryFunction),
-      this._constructDependencies(dependencies),
+      this._constructDependencies(factoryFunction, dependencies),
       false
     );
   }
 
-  toAsyncFactory(dependencies:List, factoryFunction:Function):Binding {
+  toAsyncFactory(factoryFunction:Function, {dependencies=null}={}):Binding {
     return new Binding(
       Key.get(this.token),
       reflector.convertToFactory(factoryFunction),
-      this._constructDependencies(dependencies),
+      this._constructDependencies(factoryFunction, dependencies),
       true
     );
   }
 
-  _constructDependencies(deps:List) {
-    return ListWrapper.map(deps, (t) => new Dependency(Key.get(t), false, false));
+  _constructDependencies(factoryFunction:Function, dependencies:List) {
+    return isBlank(dependencies) ?
+      reflector.dependencies(factoryFunction) :
+      ListWrapper.map(dependencies, (t) => new Dependency(Key.get(t), false, false));
   }
 }

modules/di/src/exceptions.js

@@ -77,8 +77,8 @@ export class InvalidBindingError extends Error {
 }
 
 export class NoAnnotationError extends Error {
-  constructor(type) {
-    this.message = `Cannot resolve all parameters for ${stringify(type)}`;
+  constructor(typeOrFunc) {
+    this.message = `Cannot resolve all parameters for ${stringify(typeOrFunc)}`;
   }
 
   toString() {

modules/di/src/reflector.dart

@@ -23,12 +23,13 @@ class Reflector {
     return (args) => create(name, args).reflectee;
   }
 
-  List<Dependency> dependencies(Type type) {
-    ClassMirror classMirror = reflectType(type);
-    MethodMirror ctor = classMirror.declarations[classMirror.simpleName];
+  List<Dependency> dependencies(typeOrFunc) {
+    final parameters = typeOrFunc is Type ?
+        _constructorParameters(typeOrFunc) :
+        _functionParameters(typeOrFunc);
 
-    return new List.generate(ctor.parameters.length, (int pos) {
-      ParameterMirror p = ctor.parameters[pos];
+    return new List.generate(parameters.length, (int pos) {
+      ParameterMirror p = parameters[pos];
 
       final metadata = p.metadata.map((m) => m.reflectee);
 
@@ -49,10 +50,20 @@ class Reflector {
         return new Dependency(Key.get(p.type.reflectedType), false, false);
 
       } else {
-        throw new NoAnnotationError(type);
+        throw new NoAnnotationError(typeOrFunc);
       }
     }, growable:false);
   }
+
+  List<ParameterMirror> _functionParameters(Function func) {
+    return reflect(func).function.parameters;
+  }
+
+  List<ParameterMirror> _constructorParameters(Type type) {
+    ClassMirror classMirror = reflectType(type);
+    MethodMirror ctor = classMirror.declarations[classMirror.simpleName];
+    return ctor.parameters;
+  }
 }
 
 final Reflector reflector = new Reflector();

modules/di/src/reflector.es6

@@ -14,14 +14,14 @@ class Reflector {
     return (args) => factoryFunction(...args);
   }
 
-  dependencies(type:Type):List {
-    var p = type.parameters;
-    if (p == undefined && type.length == 0) return [];
-    if (p == undefined) throw new NoAnnotationError(type);
-    return type.parameters.map((p) => this._extractToken(type, p));
+  dependencies(typeOrFunc):List {
+    var p = typeOrFunc.parameters;
+    if (p == undefined && typeOrFunc.length == 0) return [];
+    if (p == undefined) throw new NoAnnotationError(typeOrFunc);
+    return typeOrFunc.parameters.map((p) => this._extractToken(typeOrFunc, p));
   }
 
-  _extractToken(constructedType:Type, annotations) {
+  _extractToken(typeOrFunc, annotations) {
     var type;
 
     for (var paramAnnotation of annotations) {
@@ -42,7 +42,7 @@ class Reflector {
     if (isPresent(type)) {
       return this._createDependency(type, false, false);
     } else {
-      throw new NoAnnotationError(constructedType);
+      throw new NoAnnotationError(typeOrFunc);
     }
   }
 

modules/di/test/di/async_spec.js

@@ -30,7 +30,7 @@ export function main() {
     describe("asyncGet", function () {
       it('should return a future', function () {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers)
+          bind(UserList).toAsyncFactory(fetchUsers)
         ]);
         var p = injector.asyncGet(UserList);
         expect(p).toBeFuture();
@@ -64,7 +64,7 @@ export function main() {
       it('should return a future when instantiating a sync binding ' +
       'with an async dependency', function (done) {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers),
+          bind(UserList).toAsyncFactory(fetchUsers),
           UserController
         ]);
 
@@ -77,7 +77,7 @@ export function main() {
 
       it("should create only one instance (async + async)", function (done) {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers)
+          bind(UserList).toAsyncFactory(fetchUsers)
         ]);
 
         var ul1 = injector.asyncGet(UserList);
@@ -109,7 +109,7 @@ export function main() {
       it('should show the full path when error happens in a constructor', function (done) {
         var injector = new Injector([
           UserController,
-          bind(UserList).toAsyncFactory([], function () {
+          bind(UserList).toAsyncFactory(function () {
             throw "Broken UserList";
           })
         ]);
@@ -125,7 +125,7 @@ export function main() {
     describe("get", function () {
       it('should throw when instantiating an async binding', function () {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers)
+          bind(UserList).toAsyncFactory(fetchUsers)
         ]);
 
         expect(() => injector.get(UserList))
@@ -134,7 +134,7 @@ export function main() {
 
       it('should throw when instantiating a sync binding with an dependency', function () {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers),
+          bind(UserList).toAsyncFactory(fetchUsers),
           UserController
         ]);
 
@@ -144,7 +144,7 @@ export function main() {
 
       it('should resolve synchronously when an async dependency requested as a future', function () {
         var injector = new Injector([
-          bind(UserList).toAsyncFactory([], fetchUsers),
+          bind(UserList).toAsyncFactory(fetchUsers),
           AsyncUserController
         ]);
         var controller = injector.get(AsyncUserController);
@@ -155,7 +155,7 @@ export function main() {
 
       it('should wrap sync dependencies into futures if required', function () {
         var injector = new Injector([
-          bind(UserList).toFactory([], () => new UserList()),
+          bind(UserList).toFactory(() => new UserList()),
           AsyncUserController
         ]);
         var controller = injector.get(AsyncUserController);

modules/di/test/di/injector_spec.js

@@ -108,9 +108,24 @@ export function main() {
     });
 
     it('should bind to a factory', function () {
+      function sportsCarFactory(e:Engine) {
+        return new SportsCar(e);
+      }
+
+      var injector = new Injector([
+        Engine,
+        bind(Car).toFactory(sportsCarFactory)
+      ]);
+
+      var car = injector.get(Car);
+      expect(car).toBeAnInstanceOf(SportsCar);
+      expect(car.engine).toBeAnInstanceOf(Engine);
+    });
+
+    it('should support overriding factory dependencies', function () {
       var injector = new Injector([
         Engine,
-        bind(Car).toFactory([Engine], (e) => new SportsCar(e))
+        bind(Car).toFactory((e) => new SportsCar(e), {dependencies: [Engine]})
       ]);
 
       var car = injector.get(Car);
@@ -181,7 +196,7 @@ export function main() {
 
       var injector = new Injector([
         Car,
-        bind(Engine).toFactory([], () => isBroken ? new BrokenEngine() : new Engine())
+        bind(Engine).toFactory(() => isBroken ? new BrokenEngine() : new Engine())
       ]);
 
       expect(() => injector.get(Car)).toThrow();