generic Class in Python-CodePudding

I want to do a generic class in Python with one method

This class does not generate its instances
Some attributes are set in the body of the class
Method of this class uses the set attributes and in the generated classes the output of this method depends on these attributes
Method has only one input

I know that without metaclasses will not do, but I do not know how to apply them :)

something like this:

class GenericClass:
  attr_a = ''
  attr_b = ''
  def count(text):
    return len(text)/attr_a   attr_b

class A(GenericClass):
  attr_a = 2
  attr_b = 1

text = "Hello, I'm under the water"
print(A.count(text))
# 14

CodePudding user response：

Defining count as a class method would make that work:

@classmethod
def count(cls, text):
    return len(text) / cls.attr_a   cls.attr_b

CodePudding user response：

class GenericClass:
    def _count(text, a, b):
        return len(text)/a   b

class A(GenericClass):
    attr_a = 2
    attr_b = 1

    def count(text):
        return GenericClass._count(text, A.attr_a, A.attr_b)
    
text = "Hello, I'm under the water"
print(A.count(text))

CodePudding user response：

You could use @staticmethod annotation. Like this:

class GenericClass:

  attr_a = ''
  attr_b = ''

  @staticmethod
  def count(text):
    return len(text)/GenericClass.attr_a   GenericClass.attr_b

class A(GenericClass):
  GenericClass.attr_a = 2
  GenericClass.attr_b = 1


text = "Hello, I'm under the water"
print(A.count(text)) #14

You could also use @classmethod annotation if you want to know the specific class.Check out this question: Creating a static class with no instances