Programming Ruby 3.3

Blocks and Enumeration

In our program that wrote out the results of our word frequency analysis, we had the following loop:

top_five.reverse_each do |word, count|
  puts "#{word}:  #{count}"
end

The method reverse_each is an example of an iterator—a general term for a method that invokes a block of code repeatedly. Ruby also uses the term enumerator for such a method.

The most general iterator in Ruby is each, which takes a block and invokes the block once for each element in the collection. In this case, we’re using reverse_each, a shortcut method that invokes the block once for each element of the list, but in reverse order.

Enumerator methods can have different behaviors beyond just executing the block of code. A Ruby ...