The best way of learning is by reading and extracting.

Here is a lesson from 37 Signal’s Writebook code base.

I’ve extracted it as a quiz for you:

# how would you convert this array:
color_array = ["black", "blue", "green", "magenta", "orange", "violet", "white"] 

# into this hash:
color_hash = {"black"=>"black", "blue"=>"blue", 
              "green"=>"green", "magenta"=>"magenta", 
              "orange"=>"orange", "violet"=>"violet", 
              "white"=>"white"}

# and do so eloquently?

Answer:

%w[ black blue green magenta 
    orange violet white ].index_by(&:itself)
# => {"black"=>"black", "blue"=>"blue", 
#     "green"=>"green", "magenta"=>"magenta", 
#     "orange"=>"orange", "violet"=>"violet", "white"=>"white"}

Let’s break down the above:

• what does %w mean?? Results in an array of strings.
• What does index_by mean? Basically it converts an enumerable into a hash.
• itself. I had never heard of that. But it is a ruby method which returns the object itself.

Shamelessly extracted from Basecamp’s Writebook, for your learning pleasure:

class Book < ApplicationRecord
  # ... 

  enum :theme, %w[ black blue green magenta orange violet white ].index_by(&:itself), suffix: true, default: :blue  
end

The only way of learning is by reading and implementing it yourself.

Permissions

I thank the creators of Basecamp for releasing Writebook!

I have extracted snippets purely for pedagogical purposes.

However, I have not sought permission to do this, and it is entirely possible that someone might object - if so, pls send me a msg and this post will be removed, no questions asked.