Implemented simple dependency injection based only on dependency name.

.gitignore

@@ -2,3 +2,4 @@ pkg/*
 *.gem
 .bundle
 .rvmrc
+tags

Rakefile

@@ -9,3 +9,5 @@ RSpec::Core::RakeTask.new(:spec) do |t|
   t.pattern = "./spec/**/*_spec.rb"
   t.rspec_opts = ["--profile --color --format=documentation"]
 end
+
+task :default => :spec

lib/dependor.rb

@@ -1,8 +1,17 @@
 require 'dependor/injectable.rb'
 require 'dependor/meta_data.rb'
+require 'dependor/injector.rb'
+require 'dependor/dependency_to_class_name_converter.rb'
 
-module Fake
+module Dependor
+  def self.dependency_to_class_name_converter
+    @dependency_to_class_name_converter ||= DependencyToClassNameConverter.new
+  end
+
+  def self.injector
+    @injector ||= Injector.new(dependency_to_class_name_converter)
+  end
 end
 
-module Dependor
+module Fake
 end

lib/dependor/dependency_to_class_name_converter.rb

@@ -0,0 +1,20 @@
+module Dependor
+  class DependencyToClassNameConverter
+
+    def convert(dependency_name)
+      class_name = dashes_to_colons(dependency_name.to_s)
+      return camelize(class_name)
+    end
+
+    private
+
+    def camelize(string)
+      string.gsub(/^[a-z]/){|s| s.upcase}.gsub(/_+/, '_').gsub(/_[a-z]/){|s| s[1].upcase}
+    end
+
+    def dashes_to_colons(string)
+      string.gsub('-', '::_')
+    end
+
+  end
+end

lib/dependor/injectable.rb

@@ -8,7 +8,7 @@ def self.included(klass)
 
     module InstanceMethods
       def inject!
-        self
+        Dependor.injector.inject(self)
       end
     end
 

lib/dependor/injector.rb

@@ -0,0 +1,35 @@
+module Dependor
+  class Injector
+
+    attr_reader :dependency_to_class_name_converter
+
+    def initialize(dependency_to_class_name_converter)
+      @dependency_to_class_name_converter = dependency_to_class_name_converter
+    end
+
+    def inject(instance)
+      meta_data = Dependor::MetaData.for(instance)
+
+      meta_data.dependencies.each do |dependency_name|
+        klass = class_for_name(dependency_name)
+        dependency = inject(klass.new)
+        instance.send("#{dependency_name}=", dependency)
+      end
+
+      return instance
+    end
+
+    private
+
+    def class_for_name(dependency_name)
+      class_name = dependency_to_class_name_converter.convert(dependency_name)
+      parts = class_name.split('::')
+      context = Object
+      parts.each do |part|
+        context = context.const_get(part)
+      end
+      return context
+    end
+
+  end
+end

lib/dependor/meta_data.rb

@@ -17,6 +17,8 @@ def dependencies
     def self.for(klass)
       if klass.respond_to?(:dependor_meta_data)
         return klass.dependor_meta_data
+      elsif !klass.is_a?(Class)
+        return self.for(klass.class)
       else
         return EmptyMetaData.new
       end

spec/dependor/dependency_to_class_name_converter_spec.rb

@@ -0,0 +1,29 @@
+require File.expand_path('../../spec_helper.rb', __FILE__)
+
+describe Dependor::DependencyToClassNameConverter do
+
+  before(:each) do
+    @converter = Dependor::DependencyToClassNameConverter.new
+  end
+
+  it "should convert simple names to camel case" do
+    @converter.convert(:foo).should == "Foo"
+  end
+
+  it "should convert multi part underscore_names to CamelCase" do
+    @converter.convert(:some_component).should == "SomeComponent"
+  end
+
+  it "should convert - to :: in names" do
+    @converter.convert("some_module-some_class").should == "SomeModule::SomeClass"
+  end
+
+  it "should leave camelcase names unchanged" do
+    @converter.convert("SomeClass").should == "SomeClass"
+  end
+
+  it "should leave camelcase names with :: in them unchanged" do
+    @converter.convert("SomeModule::SomeClass").should == "SomeModule::SomeClass"
+  end
+
+end

spec/dependor/injectable_spec.rb

@@ -2,40 +2,6 @@
 
 describe Dependor::Injectable do
 
-  class Foo
-    def name
-      "world"
-    end
-  end
-
-  class Fake::Foo
-    def name
-      "fake"
-    end
-  end
-
-  class Bar
-    include Dependor::Injectable
-
-    depends_on :foo
-
-    def hello
-      return "Hello #{foo.name}!"
-    end
-  end
-
-  class Fake::Bar
-    def hello
-      "Hello?"
-    end
-  end
-
-  class Baz
-    include Dependor::Injectable
-
-    depends_on :bar
-  end
-
   describe ".make" do
     let(:baz) { Baz.make }
 
@@ -77,7 +43,7 @@ class DependencyInheritanceChild < DependencyInheritanceParent
     end
 
     it "should inject both parent and child dependencies" do
-      sample = DependencyInheritanceChild.new
+      sample = DependencyInheritanceChild.make
 
       sample.foo.should be_an_instance_of(Foo)
       sample.bar.should be_an_instance_of(Bar)

spec/dependor/injector_spec.rb

@@ -0,0 +1,43 @@
+require File.expand_path('../../spec_helper.rb', __FILE__)
+
+describe Dependor::Injector do
+
+  before(:each) do
+    @injector = Dependor::Injector.new(Dependor::DependencyToClassNameConverter.new)
+  end
+
+  describe "for an instance of a class with no dependencies" do
+    class NoDependenciesSample
+      attr_accessor :foo
+    end
+
+    it "should do nothing" do
+      instance = NoDependenciesSample.new
+
+      @injector.inject(instance)
+
+      instance.foo.should be_nil
+    end
+  end
+
+  describe "for an instance of a class with dependencies" do
+    it "should inject those dependencies" do
+      bar = Bar.new
+
+      @injector.inject(bar)
+
+      bar.foo.should be_an_instance_of(Foo)
+    end
+  end
+
+  describe "for a multi-level dependency hierarchy" do
+    it "should inject dependencies of dependencies too" do
+      baz = Baz.new
+
+      @injector.inject(baz)
+
+      baz.bar.foo.should be_an_instance_of(Foo)
+    end
+  end
+
+end

spec/dependor/meta_data_spec.rb

@@ -53,4 +53,20 @@ class InheritingFromClassWithNoDependenciesSample < NoMetaDataSample
     end
   end
 
+  describe "for an instance of a class with no dependencies declared" do
+    it "should return empty metadata" do
+      metadata = Dependor::MetaData.for(NoMetaDataSample.new)
+
+      metadata.dependencies.should == Set.new
+    end
+  end
+
+  describe "for an instance of a class with some dependencies declared" do
+    it "should return the same metadata as for the class" do
+      metadata = Dependor::MetaData.for(SomeDependenciesSample.new)
+
+      metadata.dependencies.should == Set.new([:foo, :bar])
+    end
+  end
+
 end

spec/sample_classes.rb

@@ -0,0 +1,33 @@
+class Foo
+  def name
+    "world"
+  end
+end
+
+class Fake::Foo
+  def name
+    "fake"
+  end
+end
+
+class Bar
+  include Dependor::Injectable
+
+  depends_on :foo
+
+  def hello
+    return "Hello #{foo.name}!"
+  end
+end
+
+class Fake::Bar
+  def hello
+    "Hello?"
+  end
+end
+
+class Baz
+  include Dependor::Injectable
+
+  depends_on :bar
+end

spec/spec_helper.rb

@@ -5,6 +5,8 @@
 
 require 'dependor'
 
+require File.expand_path('../sample_classes.rb', __FILE__)
+
 RSpec.configure do |c|
   c.color_enabled = true
 end