state.py

# ------------------------------
# State Design Pattern
# ------------------------------
# Allow an object to alter its behavior when its internal state changes. The object will appear to change its class.

fromabcimportABC, abstractmethod

classState(ABC):
defhandle_state(self):
pass

classStateA(State):
defhandle_state(self):
print('State changed to StateA.')

classStateB(State):
defhandle_state(self):
print('State changed to StateB.')

classContext(State):
def__init__(self):
self.state=None

defset_state(self, state):
self.state=state

defhandle_state(self):
self.state.handle_state()


context=Context()
stateA=StateA()
context.set_state(stateA)
context.handle_state()

print('-------------------------------------')

stateB=StateB()
context.set_state(stateB)
context.handle_state()