Question

I am reading Programming Ruby 1.9 (3rd edition): The Pragmatic Programmers’ Guide, and have a question about one of the code examples.

On page 101, there is this example:

class VowelFinder
    include Enumerable
    def initialize(string)
        @string = string
    end
    def each
        @string.scan(/[aeiou]/) do |vowel|
            yield vowel
        end
    end
end

vf = VowelFinder.new("the quick brown fox jumped")
vf.inject(:+)   # =>    "euiooue"

In the each method, each matching result from scan is passed to the block, where yield is called. But what exactly is the yield vowel line doing? From what I understand, yield is used to call a block (that was passed to a method) from within a method. What is it doing in this situation?

Answer 1

It’s calling the block that’s passed to the method, just as you understand.