evaluation.rb

class FirstTry
  attr_accessor :data

  def default_content
    @data ||= begin
      puts "First function call"
      puts "second function call"
      5
    end
  end
end

class SecondTry
  attr_accessor :data

  def default_content
    @data ||= method_wrap
  end

  def method_wrap
    puts "First function call"
    puts "second function call"
    5
  end
end

class ThirdTry
  attr_accessor :data

  def default_content
    @data ||= lambda {
      puts "First function call"
      puts "second function call"
      5
    }.call()
  end
end

a = FirstTry.new
b = SecondTry.new
c = ThirdTry.new

puts a.default_content
puts a.default_content

a.data = 'hi'
puts a.default_content

puts 'B gives the same behavior'

puts b.default_content
puts b.default_content

b.data = 'hi'

puts b.default_content

puts 'C gives the same behavior'

puts c.default_content
puts c.default_content

c.data = 'hi'

puts c.default_content

That's correct, and from those three, the first one wins in my opinion.