Add Demodulize A Class Name as a rails til

README.md

@@ -249,6 +249,7 @@ _390 TILs and counting..._
 - [Conditional Class Selectors in Haml](rails/conditional-class-selectors-in-haml.md)
 - [Creating Records of Has_One Associations](rails/creating-records-of-has-one-associations.md)
 - [Custom Validation Message](rails/custom-validation-message.md)
+- [Demodulize A Class Name](rails/demodulize-a-class-name.md)
 - [Hash Slicing](rails/hash-slicing.md)
 - [Ignore Poltergeist JavaScript Errors](rails/ignore-poltergeist-javascript-errors.md)
 - [Migrating Up Down Up](rails/migrating-up-down-up.md)

rails/demodulize-a-class-name.md

@@ -0,0 +1,28 @@
+# Demodulize A Class Name
+
+If you call `.class.name` on an instance of some class, the fully qualified
+name will be returned, module names and all. Consider the following example
+class:
+
+```ruby
+module One
+  module Two
+    class Three
+      ...
+    end
+  end
+end
+```
+
+```ruby
+> One::Two::Three.new.class.name
+#=> "One::Two::Three"
+```
+
+If you just want the unqualified class name; modules not included, you can
+use the `#demodulize` method provided by `ActiveSupport`.
+
+```ruby
+> One::Two::Three.new.class.name.demodulize
+#=> "Three"
+```