death_of_ifs.rb

# Assuming your execute command is more complex than a simple puts,
# you will need separate classes

class GoodbyeCommand
  def execute
    # complex logic here
  end
end

class TwitterCommand
  def execute
    # complex logic here
  end
end


def process(input)
  begin
    "#{input.camelize}Command".constantize.new.execute
  rescue NameError
  end 
end