Simpify design.

.rspec

@@ -1,2 +1,4 @@
 --format documentation
 --color
+--require spec_helper
+--warnings

README.md

@@ -20,52 +20,25 @@ Add this line to your application's Gemfile:
 gem 'rack-freeze'
 ```
 
-And then execute:
-
-    $ bundle
-
-Or install it yourself as:
-
-    $ gem install rack-freeze
-
 ## Usage
 
-For existing rack middleware, simply wrap it:
+Add this to your config.ru:
 
 ```ruby
-use Rack::Freeze[Rack::Logger]
+require 'rack/freeze'
 ```
 
-This will make a subclass of `Rack::Logger` if required with a working implementation of `#freeze`.
-
-In your `config.ru`, you prepare your app using the `#warmup method`;
-
-```ruby
-warmup do |app|
-	# Recursively freeze all the middleware so that mutation bugs are detected.
-	app.freeze
-end
-```
+Now all your middleware will be frozen by default.
 
 ### What bugs does this fix?
 
-So, instead of writing
+It guarantees, within the limits of the freeze API, that middleware won't mutate during a request.
 
 ```ruby
-use External::Middleware
+use Middleware
 ```
 
-you write
-
-```ruby
-use Rack::Freeze[External::Middleware]
-```
-
-That ensures that `External::Middleware` will correctly freeze itself and all subsequent apps. Additionally, if `External::Middleware` mutates it's state, it will throw an exception. In a multi-threaded web-server, unprotected mutation of internal state will lead to undefined behavior.
-
-### Thar be the Monkeys
-
-Some Rack middleware is not easy to patch in a generic way, e.g. `Rack::URLMap`. As these are identified, they will be monkey patched by this gem automatically. Going forward, I hope to bring attention to this issue and ideally integrate these changes directly into Rack.
+If `Middleware` mutates it's state, it will throw an exception. In a multi-threaded web-server, unprotected mutation of internal state will lead to undefined behavior.
 
 ## Contributing
 

lib/rack/freeze.rb

@@ -20,34 +20,5 @@
 
 require_relative 'freeze/version'
 
-require_relative 'freeze/sendfile'
-require_relative 'freeze/show_exceptions'
-require_relative 'freeze/urlmap'
-
-module Rack
-	module Freeze
-		# Check if the given klass overrides `Kernel#freeze`.
-		def self.implements_freeze?(klass)
-			klass.instance_method(:freeze).owner != Kernel
-		end
-
-		# Generate a subclass with a generic #freeze method to freeze all instance variables.
-		def self.[] klass
-			# Check if the class already has a custom implementation of #freeze.. which we assume works correctly.
-			return klass if implements_freeze?(klass)
-
-			subclass = Class.new(klass) do
-				def freeze
-					# This ensures that all class variables are frozen.
-					self.instance_variables.each do |name|
-						self.instance_variable_get(name).freeze
-					end
-
-					super
-				end
-			end
-
-			return subclass
-		end
-	end
-end
+require_relative 'freeze/freezer'
+require_relative 'freeze/builder'

lib/rack/freeze/urlmap.rb → lib/rack/freeze/builder.rb

@@ -18,15 +18,21 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 # THE SOFTWARE.
 
+require 'rack/builder'
+require_relative 'freezer'
+
 module Rack
-	class URLMap
-		def freeze
-			@map.each do |location, app|
-				location.freeze
-				app.freeze
+	module Freeze
+		module Builder
+			def use(klass, *args, &block)
+				super(Freeze[klass], *args, &block)
 			end
 
-			super
+			def to_app
+				super.freeze
+			end
 		end
 	end
+
+	Builder.prepend(Freeze::Builder)
 end

lib/rack/freeze/sendfile.rb → lib/rack/freeze/freezer.rb

@@ -19,13 +19,29 @@
 # THE SOFTWARE.
 
 module Rack
-	class Sendfile
-		def freeze
-			@app.freeze
-			@variation.freeze
-			@mappings.freeze
+	module Freeze
+		# Check if the given klass overrides `Kernel#freeze`.
+		def self.implements_freeze?(klass)
+			klass.instance_method(:freeze).owner != Kernel
+		end
+
+		# Generate a subclass with a generic #freeze method to freeze all instance variables.
+		def self.[] klass
+			# Check if the class already has a custom implementation of #freeze.. which we assume works correctly.
+			return klass if implements_freeze?(klass)
+
+			subclass = Class.new(klass) do
+				def freeze
+					# This ensures that all class variables are frozen.
+					self.instance_variables.each do |name|
+						self.instance_variable_get(name).freeze
+					end
+
+					super
+				end
+			end
 
-			super
+			return subclass
 		end
 	end
 end

lib/rack/freeze/version.rb

@@ -20,6 +20,6 @@
 
 module Rack
 	module Freeze
-		VERSION = "1.0.0"
+		VERSION = "1.1.0"
 	end
 end

rack-freeze.gemspec

@@ -2,20 +2,22 @@
 require_relative 'lib/rack/freeze/version'
 
 Gem::Specification.new do |spec|
-  spec.name          = "rack-freeze"
-  spec.version       = Rack::Freeze::VERSION
-  spec.authors       = ["Samuel Williams"]
-  spec.email         = ["[email protected]"]
+	spec.name          = "rack-freeze"
+	spec.version       = Rack::Freeze::VERSION
+	spec.authors       = ["Samuel Williams"]
+	spec.email         = ["[email protected]"]
 
-  spec.summary       = "Provides a policy for frozen rack middleware."
-  spec.homepage      = "https://github.com/ioquatix/rack-freeze"
+	spec.summary       = "Provides a policy for frozen rack middleware."
+	spec.homepage      = "https://github.com/ioquatix/rack-freeze"
 
-  spec.files         = `git ls-files -z`.split("\x0").reject do |f|
-    f.match(%r{^(test|spec|features)/})
-  end
-  spec.require_paths = ["lib"]
-
-  spec.add_development_dependency "bundler", "~> 1.14"
-  spec.add_development_dependency "rake", "~> 10.0"
-  spec.add_development_dependency "rspec", "~> 3.0"
+	spec.files         = `git ls-files -z`.split("\x0").reject do |f|
+		f.match(%r{^(test|spec|features)/})
+	end
+	spec.require_paths = ["lib"]
+
+	spec.add_dependency "rack", "~> 2.0"
+
+	spec.add_development_dependency "bundler", "~> 1.14"
+	spec.add_development_dependency "rake", "~> 10.0"
+	spec.add_development_dependency "rspec", "~> 3.0"
 end

spec/rack/freeze/builder_spec.rb

@@ -0,0 +1,41 @@
+
+RSpec.shared_context "app builder" do
+	it "should generate frozen app" do
+		# We need to give lexical scope for ruby to find it :)
+		middleware = described_class
+
+		app = Rack::Builder.new do
+			use middleware
+
+			run lambda { |env| [404, {}, []] }
+		end.to_app
+
+		expect(app.frozen?).to be_truthy
+	end
+end
+
+class NonConformingMiddleware
+	def initialize(app)
+		@app = app
+	end
+
+	def call(env)
+		return @app.call(env)
+	end
+end
+
+RSpec.describe NonConformingMiddleware do
+	include_context "app builder"
+end
+
+class ConformingMiddleware < NonConformingMiddleware
+	def freeze
+		@app.freeze
+
+		super
+	end
+end
+
+RSpec.describe ConformingMiddleware do
+	include_context "app builder"
+end

spec/rack/freeze_spec.rb → spec/rack/freeze/freezer_spec.rb

@@ -1,4 +1,3 @@
-require "spec_helper"
 
 RSpec.describe Rack::Freeze do
 	it "should detect class has \#freeze" do