使用del __builtins __.__ dict __ [“ __ import__”]删除后如何找回__import__

Question

我正在尝试编码挑战。我之前无法更改代码， del __builtins__.__dict__["__import__"]但之后必须使用导入。我需要一种恢复默认值的方法__builtins__。其python 2.7。

我试过了，__builtins__ = [x for x in (1).__class__.__base__.__subclasses__() if x.__name__ == 'catch_warnings'][0]()._module.__builtins__但是那行不通，因为对内置函数的引用还没有，但是内置函数字典中的元素已经存在。

Answer 1

In Python 2, you can use the reload function to get a fresh copy of the __builtins__ module:

>>> del __builtins__.__dict__['__import__']
>>> reload(__builtins__)
<module '__builtin__' (built-in)>
>>> __import__
<built-in function __import__>
>>>

In Python 3, the reload function has been moved to the imp module (and in Python 3.4, importlib) so importing imp or importlib isn't option without __import__. Instead, you can use __loader__.load_module to load the sys module and delete the cached but ruined copy of the builtins module from the sys.modules dict, so that you can load a new copy of the builtins module with __loader__.load_module:

>>> del __builtins__.__dict__['__import__']
>>> del __loader__.load_module('sys').modules['builtins']
>>> __builtins__ = __loader__.load_module('builtins')
>>> __import__
<built-in function __import__>
>>>