shvets / design_patterns_in_ruby

# states.bsh
 
# Allow an object to alter it's behavior when it's internal state changes.
# The object will appear to change it's class.
 
# in ruby you can achieve same goal with metaprogramming
 
# 1. state type and it's implementations
 
class State
  def handle
  end
end
 
class MyState1 < State
  def handle
    puts "handle1"
  end
end
 
class MyState2 < State
  def handle
    puts "handle2"
  end
end
 
# 2. context's type and it's implementation
 
class Context
  def set_state(state)
  end
 
  def request
  end
end
 
class MyContext < Context
  def state=(state)
    @state = state
  end
 
  def request
    @state.handle
  end
end
 
# 3. test
 
context = MyContext.new
 
state1 = MyState1.new
state2 = MyState2.new
 
context.state = state1
context.request
 
context.state = state2
context.request