block, lambda, proc, instance_eval.rb

# Understanding Ruby Blocks, Procs and Lambdas
# http://stackoverflow.com/questions/6372596/ruby-block-procs-and-instance-eval
# http://www.robertsosinski.com/2008/12/21/understanding-ruby-blocks-procs-and-lambdas/

# Metaprogramming Ruby: class_eval and instance_eval
# http://www.jimmycuadra.com/posts/metaprogramming-ruby-class-eval-and-instance-eval

my_proc = proc do
  puts "yeaaaaah"
end

puts "will it run?"

my_proc.call

def hug(&block)
  p block
  print "{"
  instance_eval(&block)
  yield
  block.call
  print "}"
end

hug { print 'wtf' }

def callbacks(procs)
  procs[:starting].call

  puts "Still going"

  procs[:finishing].call
end

callbacks(:starting => Proc.new { puts "Starting" },
          :finishing => Proc.new { puts "Finish" })