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  1. #!/usr/bin/env python3
  2.  
  3. from abc import ABCMeta, abstractmethod
  4.  
  5. class Shape_(metaclass=ABCMeta):
  6.     @abstractmethod
  7.     def calc_(self):
  8.         pass
  9.  
  10. class Shape(metaclass=ABCMeta):
  11.     @abstractmethod
  12.     def calc(self):
  13.         pass
  14.  
  15. class Rect(Shape):
  16.     def __init__(self, w, h):
  17.         self.w = w
  18.         self.h = h
  19.  
  20.     def calc(self):
  21.         area = self.w * self.h
  22.         print('area rect:', area)        
  23.  
  24. class Circle(Shape):
  25.     def __init__(self, r):
  26.         self.r = r
  27.  
  28.     def calc(self):
  29.         area = self.r * self.r * 3.14
  30.         print('area circle: ', area)
  31.  
  32.  
  33. class AreaCalc:
  34.     def calc(self, shape):
  35.         # if isinstance(shape, Shape_):     # wrong
  36.         if isinstance(shape, Shape):        # right
  37.             shape.calc()
  38.         else:
  39.             raise Exception('wrong interface') 
  40.  
  41.  
  42. circle = Circle(2)
  43. rect = Rect(4, 2)
  44. areaCalc = AreaCalc()
  45. areaCalc.calc(rect)
  46. areaCalc.calc(circle)
Success #stdin #stdout 0.02s 27656KB
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area rect: 8
area circle:  12.56
https://ideone.com/Gep3DU
language:
Python 3 (python  3.12)
created:
7 years ago
visibility:
public

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