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  1. from functools import partial, wraps
  2. from types import MethodType
  3.  
  4. class subscriptable:
  5.     _SUBSCRIPT_KEY = '___SUBSCRIPT_KEY'
  6.     _HAS_SUBSCRIPTABLE_METHODS = '___HAS_SUBSCRIPTABLE_METHODS'
  7.  
  8.     def __init__(self, method):
  9.         self._method = method
  10.  
  11.     def _bind(self, instance):
  12.         self._method = MethodType(self._method, instance)
  13.  
  14.     def __getitem__(self, specified_type, *args, **kwargs):
  15.         if not isinstance(specified_type, type):
  16.             raise TypeError("Only Type Accessors are supported - must be an instance of `type`")
  17.  
  18.         return partial(self.__call__, **{self.__class__._SUBSCRIPT_KEY: specified_type})
  19.  
  20.     def __call__(self, *args, **kwargs):
  21.         """A transparent passthrough to the wrapped method"""
  22.         return self._method(*args, **kwargs)
  23.  
  24.     def __str__(self):
  25.         return f"<{self.__class__.__name__} {self._method}>"
  26.  
  27.     @classmethod
  28.     def has_key(cls, foo_kwargs):
  29.         """A utility method to determine whether the provided kwargs has the expected subscript key"""
  30.         return cls._SUBSCRIPT_KEY in foo_kwargs
  31.  
  32.     @classmethod
  33.     def key(cls, foo_kwargs:dict):
  34.         """A utility method that allows the subscript key to be consumed by the wrapped method, without needing to know the inner workings"""
  35.         return foo_kwargs.pop(cls._SUBSCRIPT_KEY, None)
  36.  
  37.     @classmethod
  38.     def container(cls, clazz):
  39.         """A decorator for classes containing `subscriptable` methods"""
  40.         if not hasattr(clazz, cls._HAS_SUBSCRIPTABLE_METHODS):
  41.             orig_init = clazz.__init__
  42.             @wraps(clazz.__init__)
  43.             def __init__(self, *args, **kwargs):
  44.                 for attr_name in dir(self):
  45.                     attr_value = getattr(self, attr_name)
  46.                     if isinstance(attr_value, cls):
  47.                         attr_value._bind(self)
  48.                 orig_init(self, *args, **kwargs)
  49.             clazz.__init__ = __init__
  50.             setattr(clazz, cls._HAS_SUBSCRIPTABLE_METHODS, True)
  51.         return clazz
  52.  
  53. @subscriptable.container
  54. class MyClass:
  55.  
  56.     @subscriptable
  57.     def compute_typed_value(self, value, *args, **kwargs):
  58.         print(self, args, kwargs)
  59.         if subscriptable.has_key(kwargs):
  60.             value = subscriptable.key(kwargs)(value)
  61.         self.my_other_method()
  62.         return value
  63.  
  64.     def my_other_method(self):
  65.         print('Doing some other things!')
  66.         return 3
  67.  
  68.  
  69. a = MyClass()
  70. b = MyClass()
  71. value = a.compute_typed_value[int]('12345')
Runtime error #stdin #stdout #stderr 0.14s 26392KB
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stdin
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Standard input is empty
stdout
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<__main__.MyClass object at 0x14614b38dc70> ('12345',) {'___SUBSCRIPT_KEY': <class 'int'>}
stderr
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Traceback (most recent call last):
  File "./prog.py", line 71, in <module>
  File "./prog.py", line 22, in __call__
  File "./prog.py", line 60, in compute_typed_value
TypeError: int() argument must be a string, a bytes-like object or a number, not 'MyClass'
https://ideone.com/dX8iKp
language:
Python 3 (python  3.12)
created:
2 years ago
visibility:
public

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