A more readable sort by

Posted: 04/03/2009

Suppose we want to sort a collection of accounts by their account balance. We could put them in ascending order like this:

  @accounts.sort {|x,y| x.balance <=> y.balance}

Or descending order like this:

  @accounts.sort {|x,y| y.balance <=> x.balance}

To me this isn’t very readable. How about this as an alternative:

  @accounts.sort_by_ascending(:balance)
  # or 
  @accounts.sort_by_descending(:balance)

Much more readable. The implementation is pretty simple, first create the methods:

  module ReadableSortBy
    def sort_by_ascending(method)
      sort {|x, y| x.send(method) <=> y.send(method)}
    end
    def sort_by_descending(method)
      sort {|x, y| y.send(method) <=> x.send(method)}
    end
  end

Then include them in Array:

  class Array
    include ReadableSortBy
  end

You could also make sort_by_ascending! and sort_by_descending! methods that modify the collection itself. Do this by replacing sort with sort! in both cases.