Ruby block demo

block.rb

greeting_and_do_something = Proc.new do |message|
  puts "Hello, #{message}"
  yield(message) if block_given?
  puts "wish you have a good time"
  message
end

# callback demo
def trainingWithCompletion(&block)
  puts "training begin..."
  result = block.call(123)
  puts "training result = #{result}"
  puts "training complete..."
end

puts "*" * 50
trainingWithCompletion { |x|
  puts "--------------------------------"
  puts "you just pass #{x} in the block"
  puts "--------------------------------"
  x * 2 + 100
}

puts "*" * 50
trainingWithCompletion(&greeting_and_do_something)