add overwrites for class injections

lib/dependor/core_ext.rb

@@ -1,2 +1,3 @@
 Object.extend Dependor::TakesExt
+Object.extend Dependor::ClassTakesExt
 Transient = Dependor::Transient

lib/dependor/instantiator.rb

@@ -20,9 +20,9 @@ def new(klass_name, overwrites = {})
       klass.new(args)
     end
 
-    def get_class(klass_name)
+    def get_class(klass_name, overwrites = {})
       klass = @class_lookup.lookup(klass_name)
-      SubclassBuilder.subclass(klass, @injector)
+      SubclassBuilder.subclass(klass, @injector, overwrites)
     end
 
     def method_missing(name, *args, &block)

lib/dependor/subclass_builder.rb

@@ -1,12 +1,19 @@
 module Dependor
   class SubclassBuilder
-    def self.subclass(klass, injector)
+    def self.get_dependency(name, injector, overwrites)
+      return overwrites.fetch(name) { @injector[name] }
+    end
+
+    def self.subclass(klass, injector, overwrites = {})
       return klass unless klass.respond_to?(:class_takes)
 
       Class.new(klass) do
-        klass.class_takes.each do |dependency|
-          define_singleton_method dependency do
-            injector[dependency]
+        klass.class_takes.each do |name|
+          define_singleton_method name do
+            unless instance_variable_get("@#{name}")
+              instance_variable_set("@#{name}", overwrites.fetch(name) { injector[name] })
+            end
+            instance_variable_get("@#{name}")
           end
         end
       end

spec/features/automagic_injection_spec.rb

@@ -33,6 +33,10 @@ class Crown
     class MagicalSword < Sword
       extend Takes(:name)
     end
+
+    class Kingdom
+      extend ClassTakes(:king, :name)
+    end
   end
 end
 
@@ -61,6 +65,7 @@ class MagicalSword < Sword
       excalibur { new(:MagicalSword, name: "Excalibur") }
       king { arthur }
       knights { [lancelot, galahad] }
+      kingdom { get_class(:Kingdom, name: "Far Far Away") }
     end
   }
 
@@ -76,6 +81,14 @@ class MagicalSword < Sword
     expect(registry[:king]).to equal(registry[:arthur])
   end
 
+  it "allows class injections" do
+    expect(registry[:kingdom]).to be_an_instance_of(Class)
+  end
+
+  it "allows for overrides when injecting classes" do
+    expect(registry[:kingdom].name).to eq("Far Far Away")
+  end
+
   it "makes objects singletons by default" do
     first_camelot = registry[:camelot]
     second_camelot = registry[:camelot]