python-patterns/patterns/behavioral/specification.py at master · DataCraft-AI/python-patterns · GitHub

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"""
@author: Gordeev Andrey <gordeev.and.and@gmail.com>

*TL;DR
Provides recombination business logic by chaining together using boolean logic.
"""

fromabcimportabstractmethod


classSpecification:
defand_specification(self, candidate):
raiseNotImplementedError()

defor_specification(self, candidate):
raiseNotImplementedError()

defnot_specification(self):
raiseNotImplementedError()

@abstractmethod
defis_satisfied_by(self, candidate):
pass


classCompositeSpecification(Specification):
@abstractmethod
defis_satisfied_by(self, candidate):
pass

defand_specification(self, candidate):
returnAndSpecification(self, candidate)

defor_specification(self, candidate):
returnOrSpecification(self, candidate)

defnot_specification(self):
returnNotSpecification(self)


classAndSpecification(CompositeSpecification):
_one=Specification()
_other=Specification()

def__init__(self, one, other):
self._one=one
self._other=other

defis_satisfied_by(self, candidate):
returnbool(
self._one.is_satisfied_by(candidate)
andself._other.is_satisfied_by(candidate)
 )


classOrSpecification(CompositeSpecification):
_one=Specification()
_other=Specification()

def__init__(self, one, other):
self._one=one
self._other=other

defis_satisfied_by(self, candidate):
returnbool(
self._one.is_satisfied_by(candidate)
orself._other.is_satisfied_by(candidate)
 )


classNotSpecification(CompositeSpecification):
_wrapped=Specification()

def__init__(self, wrapped):
self._wrapped=wrapped

defis_satisfied_by(self, candidate):
returnbool(notself._wrapped.is_satisfied_by(candidate))


classUser:
def__init__(self, super_user=False):
self.super_user=super_user


classUserSpecification(CompositeSpecification):
defis_satisfied_by(self, candidate):
returnisinstance(candidate, User)


classSuperUserSpecification(CompositeSpecification):
defis_satisfied_by(self, candidate):
returngetattr(candidate, "super_user", False)


defmain():
"""
 >>> andrey = User()
 >>> ivan = User(super_user=True)
 >>> vasiliy = 'not User instance'

 >>> root_specification = UserSpecification().and_specification(SuperUserSpecification())

 # Is specification satisfied by <name>
 >>> root_specification.is_satisfied_by(andrey), 'andrey'
 (False, 'andrey')
 >>> root_specification.is_satisfied_by(ivan), 'ivan'
 (True, 'ivan')
 >>> root_specification.is_satisfied_by(vasiliy), 'vasiliy'
 (False, 'vasiliy')
 """


if__name__=="__main__":
importdoctest

doctest.testmod()