python-patterns/patterns/other/blackboard.py at master · faif/python-patterns · GitHub

Name: python-patterns/patterns/other/blackboard.py at master · faif/python-patterns · GitHub
Rating: 4.6 (2820 reviews)
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"""
@author: Eugene Duboviy <eugene.dubovoy@gmail.com> | github.com/duboviy

In Blackboard pattern several specialised sub-systems (knowledge sources)
assemble their knowledge to build a possibly partial or approximate solution.
In this way, the sub-systems work together to solve the problem,
where the solution is the sum of its parts.

https://en.wikipedia.org/wiki/Blackboard_system
"""

from __future__ importannotations

importabc
importrandom


classBlackboard:
def__init__(self) ->None:
self.experts= []
self.common_state= {
"problems": 0,
"suggestions": 0,
"contributions": [],
"progress": 0, # percentage, if 100 -> task is finished
 }

defadd_expert(self, expert: AbstractExpert) ->None:
self.experts.append(expert)


classController:
def__init__(self, blackboard: Blackboard) ->None:
self.blackboard=blackboard

defrun_loop(self):
"""
 This function is a loop that runs until the progress reaches 100.
 It checks if an expert is eager to contribute and then calls its contribute method.
 """
whileself.blackboard.common_state["progress"] <100:
forexpertinself.blackboard.experts:
ifexpert.is_eager_to_contribute:
expert.contribute()
returnself.blackboard.common_state["contributions"]


classAbstractExpert(metaclass=abc.ABCMeta):
def__init__(self, blackboard: Blackboard) ->None:
self.blackboard=blackboard

@property
@abc.abstractmethod
defis_eager_to_contribute(self):
raiseNotImplementedError("Must provide implementation in subclass.")

@abc.abstractmethod
defcontribute(self):
raiseNotImplementedError("Must provide implementation in subclass.")


classStudent(AbstractExpert):
@property
defis_eager_to_contribute(self) ->bool:
returnTrue

defcontribute(self) ->None:
self.blackboard.common_state["problems"] +=random.randint(1, 10)
self.blackboard.common_state["suggestions"] +=random.randint(1, 10)
self.blackboard.common_state["contributions"] += [self.__class__.__name__]
self.blackboard.common_state["progress"] +=random.randint(1, 2)


classScientist(AbstractExpert):
@property
defis_eager_to_contribute(self) ->int:
returnrandom.randint(0, 1)

defcontribute(self) ->None:
self.blackboard.common_state["problems"] +=random.randint(10, 20)
self.blackboard.common_state["suggestions"] +=random.randint(10, 20)
self.blackboard.common_state["contributions"] += [self.__class__.__name__]
self.blackboard.common_state["progress"] +=random.randint(10, 30)


classProfessor(AbstractExpert):
@property
defis_eager_to_contribute(self) ->bool:
returnTrueifself.blackboard.common_state["problems"] >100elseFalse

defcontribute(self) ->None:
self.blackboard.common_state["problems"] +=random.randint(1, 2)
self.blackboard.common_state["suggestions"] +=random.randint(10, 20)
self.blackboard.common_state["contributions"] += [self.__class__.__name__]
self.blackboard.common_state["progress"] +=random.randint(10, 100)


defmain():
"""
 >>> blackboard = Blackboard()
 >>> blackboard.add_expert(Student(blackboard))
 >>> blackboard.add_expert(Scientist(blackboard))
 >>> blackboard.add_expert(Professor(blackboard))

 >>> c = Controller(blackboard)
 >>> contributions = c.run_loop()

 >>> from pprint import pprint
 >>> pprint(contributions)
 ['Student',
 'Student',
 'Student',
 'Student',
 'Scientist',
 'Student',
 'Student',
 'Student',
 'Scientist',
 'Student',
 'Scientist',
 'Student',
 'Student',
 'Scientist',
 'Professor']
 """


if__name__=="__main__":
random.seed(1234) # for deterministic doctest outputs
importdoctest

doctest.testmod()