selfloading.rb

# The following code can be used to reload a
# running application with updated code, for example
# in a unicorn process.
#

# In e.g. a file loader.rb
#
module Loader
  
  def self.selfload
    @@selfload
  end
  def self.selfload= value
    @@selfload = value
  end
  @@selfload = true
  
  def self.selfload!
    exclaim 'Loader loading itself.'
    load __FILE__ # load self
    Loader.selfload = false
    load!
  end
  
  def self.load!
    return selfload! if selfload
    
    #
    # Load your application here using load, not require.
    #

  end

end

# Somewhere else...
#
# Installing a signal that lets the user send the USR1
# signal to the application to reload it.
#
Signal.trap 'USR1' do
  Loader.load!
end

# Then for example in the Terminal
#
kill -USR1 <pid>