Early in my Ruby career, I found myself needing access to the index while using Enumerable methods such as map and select. I quickly discovered the obscurely documented enum_for method:
Since MacPorts is now on Ruby 1.8.7, I read the 1.8.7 summary log and noticed a bunch of existing methods that now "Return an enumerator if no block is given." I soon realized that the above can now be written as:
It's a seemingly simple and minor improvement, but I think this change will encourage developers to use Enumerator more often with Ruby. For example, the enum_for method is never used in Rails 2.1. Contrarily, I bet that the new "Return an enumerator if no block is given" change will be used in Rails (eventually).
Arbitrary Uses
Since Integer#downto returns an Enumerator, let's write factorial:
Why not sort the letters in a word? Let's combine each_char with sort:
Since Enumerator is just an object, we can pass it around, and customize how other methods behave. For example, here I determine whether the items are processed in ascending or descending order:
All of this fun can be added to prior versions of Ruby by opening classes. I think this might work...
Please comment and let me know if there are better uses for this change!
