improve header lookup time

Author: Asmod4n

lib/webmachine/request.rb

@@ -30,9 +30,18 @@ def initialize(method, uri, headers, body)
     # lowercased-underscored version of the header name, e.g.
     # `if_unmodified_since`.
     def method_missing(m, *args, &block)
-      if m.to_s =~ HTTP_HEADERS_MATCH
+      if m =~ HTTP_HEADERS_MATCH
         # Access headers more easily as underscored methods.
-        self[m.to_s.tr(UNDERSCORE, DASH)]
+        header_name = m.to_s.tr(UNDERSCORE, DASH)
+        if (header_value = headers[header_name])
+          # Make future lookups faster.
+          self.class.class_eval <<-RUBY, __FILE__, __LINE__
+          def #{m}
+            headers["#{header_name}"]
+          end
+          RUBY
+        end
+        header_value
       else
         super
       end

memory_test.rb

@@ -28,7 +28,7 @@ def to_html
 CONSTANTIZED = '/constantized'.freeze
 require 'memory_profiler'
 report = MemoryProfiler.report do
-  5.times do
+  100.times do
     session.get(CONSTANTIZED)
   end
 end