Создание абстрактного класса в Python

Question

Я работал над тем, чтобы сделать EFeatureObjective абстрактным, я знал, что могу реализовать класс и просто сделать calculate_feature_scores абстрактным, но то, что я сделал -

class EFeatureObjective(bluepyopt.objectives.Objective):

    """EPhys feature objective"""

    def __init__(self, name, features=None):
        """Constructor
        Args:
            name (str): name of this object
            features (list of eFeatures): features used in the Objective
        """

        super(EFeatureObjective, self).__init__(name)
        self.name = name
        self.features = features

    def calculate_feature_scores(self, responses):
        """Calculate the scores for the individual features"""

        scores = []
        for feature in self.features:
            scores.append(feature.calculate_score(responses))

        return scores


class SingletonObjective(EFeatureObjective):

    """Single EPhys feature"""

    def __init__(self, name, feature):
        """Constructor
        Args:
            name (str): name of this object
            features (EFeature): single eFeature inside this objective
        """

        super(SingletonObjective, self).__init__(name, [feature])

    def calculate_score(self, responses):
        """Objective score"""

        return self.calculate_feature_scores(responses)[0]

    def __str__(self):
        """String representation"""

        return '( %s )' % self.features[0]

• Я сделал EFeatureObjective как абстрактный, используя ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()}) и имел

      def calculate_feature_scores(self, responses):                                   
           pass
  

  как

   import abc                                                                           
  
   ABC = abc.ABCMeta('ABC', (object,), {'__slots__': ()})                               
  
  
   class EFeatureObjective(bluepyopt.objectives.Objective, ABC):                           
  
        """EPhys feature objective"""                                                       
        def __init__(self, name, features=None):                                            
              """Constructor                                                                  
  
              Args:                                                                           
              name (str): name of this object                                             
              features (list of eFeatures): features used in the Objective                
              """                                                                             
  
              super(EFeatureObjective, self).__init__(name)                                   
              self.name = name                                                                
              self.features = features                                                        
  
        @abc.abstractmethod                                                                 
        def calculate_feature_scores(self, responses):    
            pass
  
  
   class SingletonObjective(EFeatureObjective):
         .........
         def calculate_feature_scores(self, responses):                                   
             """Calculate the scores for the individual features"""                       
  
             scores = []                                                                  
             for feature in self.features:                                                
             scores.append(feature.calculate_score(responses))                        
  
             return scores     
  

  Затем я реализовал этот метод в SingletonObjective, проблема в синтаксисе, может ли это быть реализовано? features недоступны в SingletonObjective. В основном EFeatureObjective работает на (list of eFeatures), а SingletonObjective работает на single eFeature inside this objective.

• Затем я назвал абстрактный класс EFeatureObjective абстрактный метод calculate_feature_scores внутри SingletonObjective как

   def calculate_feature_scores(self, responses):
       super(SingletonObjective, self).calculate_feature_scores(responses)
  

  но потом

   def calculate_score(self, responses):                                               
           """Objective score"""                                                           
  
           return self.calculate_feature_scores(responses)[0]  
  

  индекс будет ошибка.

Я потратил некоторое время на это, и теперь я хочу, чтобы EFeatureObjective был абстрактным, не создавая класс, работающий с различными версиями Python. Ценю любые ответы.

Answer 1

Если вам нужен класс, который вы не можете создать, но можете создать подкласс, то вот способ сделать это:

class BaseClass(object):
  def __new__(cls):
    ''' If this is not a subclass being instanciated, then raise an error '''
    if cls is BaseClass:
      raise TypeError('Cannot instantiate this')
    return object.__new__(cls)

   AbstractMethod1 = None

   def __init_subclass__(cls):
     ''' Anytime subclasses are created, make sure they have the right methods '''
     if cls.AbstractMethod1 is None:
       raise TypeError('All subclasses of `base` must define `AbstractMethod1`')