Add Convert A Symbol To A Constant as a rails til

README.md

@@ -7,7 +7,7 @@ variety of languages and technologies. These are things that don't really
 warrant a full blog post. These are mostly things I learn by pairing with
 smart people at [Hashrocket](http://hashrocket.com/).
 
-_495 TILs and counting..._
+_496 TILs and counting..._
 
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@@ -313,6 +313,7 @@ _495 TILs and counting..._
 - [Capybara Page Status Code](rails/capybara-page-status-code.md)
 - [Code Statistics For An Application](rails/code-statistics-for-an-application.md)
 - [Conditional Class Selectors in Haml](rails/conditional-class-selectors-in-haml.md)
+- [Convert A Symbol To A Constant](rails/convert-a-symbol-to-a-constant.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)

rails/convert-a-symbol-to-a-constant.md

@@ -0,0 +1,23 @@
+# Convert A Symbol To A Constant
+
+If you have a symbol and need to convert it to a constant, perhaps because
+of some metaprogramming induced by a polymorphic solution, then you may
+start off on an approach like the following. In fact, I've seen a number of
+StackOverflow solutions like this.
+
+```ruby
+:module.to_s.capitalize.constantize
+#=> Module
+```
+
+That is great for one-word constant names, but what about multi-word
+constants like `OpenStruct`. This approach will not work for the symbol
+`:open_struct`. We need a more general solution.
+
+The key is to ditch `#capitalize and instead use another ActiveSupport
+method, `#classify`.
+
+```ruby
+:open_struct.to_s.classify.constantize
+#=> OpenStruct
+```