1. import abc
  3. class FormalParserInterface(metaclass=abc.ABCMeta):
  4.     @classmethod
  5.     def __subclasshook__(cls, subclass):
  6.         return (hasattr(subclass, 'load_data_source') and 
  7.                 callable(subclass.load_data_source) and 
  8.                 hasattr(subclass, 'extract_text') and 
  9.                 callable(subclass.extract_text) or 
  10.                 NotImplemented)
  12.     @abc.abstractmethod
  13.     def load_data_source(self, path: str, file_name: str):
  14.         """Load in the data set"""
  15.         raise NotImplementedError
  17.     @abc.abstractmethod
  18.     def extract_text(self, full_file_path: str):
  19.         """Extract text from the data set"""
  20.         raise NotImplementedError
  22. class PdfParserNew(FormalParserInterface):
  23.     """Extract text from a PDF."""
  24.     def load_data_source(self, path: str, file_name: str) -> str:
  25.         """Overrides FormalParserInterface.load_data_source()"""
  26.         print("i am pdfparser")
  27.         pass
  29.     def extract_text(self, full_file_path: str) -> dict:
  30.         """Overrides FormalParserInterface.extract_text()"""
  31.         pass
  33. class EmlParserNew(FormalParserInterface):
  34.     """Extract text from an email."""
  35.     def load_data_source(self, path: str, file_name: str) -> str:
  36.         """Overrides FormalParserInterface.load_data_source()"""
  37.         print("i amd eml parser")
  38.         pass
  40.     def extract_text(self, full_file_path: str) -> dict:
  41.         """A method defined only in EmlParser.
  42.         Does not override FormalParserInterface.extract_text()
  43.         """
  44.         pass
  47. my_pdf_parser = PdfParserNew()
  48. my_eml_parser = EmlParserNew()
  50. parser_list = [my_pdf_parser, my_eml_parser]
  52. for each_parser in parser_list:
  53.     each_parser.load_data_source("", "")

参考资料

https://realpython.com/python-interface/#using-abstract-method-declaration