Implement support for declaring promise/future methods natively

Fixes #7

Gemfile

@@ -6,6 +6,7 @@ gemspec
 group :development do
   gem 'rake'
   gem 'rspec'
+  gem 'rspec-its'
   gem 'pry'
   gem 'debugger-pry', :platform => :mri_19
 end

lib/typedeaf/classmethods.rb

@@ -1,3 +1,5 @@
+require 'concurrent'
+
 require 'typedeaf/arguments'
 require 'typedeaf/errors'
 
@@ -7,6 +9,18 @@ module Typedeaf
       return Typedeaf::Arguments::DefaultArgument.new(value, *types)
     end
 
+    def promise(method_sym, params={}, &block)
+      define(method_sym, params) do
+        Concurrent::Promise.new { block.call }.execute
+      end
+    end
+
+    def future(method_sym, params={}, &block)
+      define(method_sym, params) do
+        Concurrent::Future.new { block.call }.execute
+      end
+    end
+
     def define(method_sym, params={}, &block)
       if block.nil?
         raise MissingMethodException,

spec/spec_helper.rb

@@ -1,6 +1,9 @@
 require 'rubygems'
 require 'typedeaf'
 
+require 'rspec'
+require 'rspec/its'
+
 unless RUBY_PLATFORM == 'java'
   require 'debugger/pry'
 end

spec/typedeaf_spec.rb

@@ -25,7 +25,6 @@ describe Typedeaf do
       end
     end
 
-
     context 'defining a method with no arguments' do
       before :each do
         klass.class_eval do
@@ -142,5 +141,45 @@ describe Typedeaf do
         expect(called).to be_truthy
       end
     end
+
+    context 'defining a future method' do
+      before :each do
+        klass.class_eval do
+          future :log, message: String do
+            'hello'
+          end
+        end
+      end
+
+      it { should respond_to :log }
+
+      context 'the method result' do
+        let(:msg) { 'hello' }
+        subject(:result) { instance.log(msg) }
+
+        it { should be_kind_of Concurrent::Future }
+        its(:value) { should eql(msg) }
+      end
+    end
+
+    context 'defining a promise method' do
+      before :each do
+        klass.class_eval do
+          promise :log, message: String do
+            'hello'
+          end
+        end
+      end
+
+      it { should respond_to :log }
+
+      context 'the method result' do
+        let(:msg) { 'hello' }
+        subject(:result) { instance.log(msg) }
+
+        it { should be_kind_of Concurrent::Promise }
+        its(:value) { should eql(msg) }
+      end
+    end
   end
 end

typedeaf.gemspec

@@ -16,4 +16,6 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
   spec.require_paths = ["lib"]
+
+  spec.add_dependency 'concurrent-ruby', '~> 0.7.0'
 end