如何替换导入库中的导入？

Question

假设，我们有 3 个文件：

library1.py:

SomeVariable = '1'

library2.py:

import library1
print(library1.SomeVariable)

library3.py:

SomeVariable = '2'

我的目标是在 library2.py 中“更改”library1 导入（不仅是 1 个变量），因此结果输出将为“2” （也就是说，将library2.py中library1的缓存替换为library3）

Answer 1

你可以使用复制

import copy
b = copy.copy(lib1.a)
...
print(lib2.b)

Answer 2

我找到了一种方法：

import library1,library2,library3
import importlib

for i in library3.__dict__.keys():
    library1.__dict__[i] = library3.__dict__[i]
library2 = importlib.reload(library2)

Answer 3

警告：此方法非常 hacky，你可能可能会破坏东西。

假设我们有这个 library1.py:

var1 = 100
var2 = 'never gonna give you up'
a = 3.1415926

而且，我们想用overwrite.py覆盖它：

var1 = -9999
var2 = 'never gonna let you down'
a = 2.71828

如果我们进入 shell，我们可以看到一个模块有一个 __dict__ 属性，它包含它内部的所有内容。

>>> import library1
>>> library1.__dict__
# NOTE: This also contains a bunch of python's variables, including their builtins, magic things like `__name__`, etc
# I cut them out for simplicity
{'var1': 100, 'var2': 'never gonna give you up', 'a': 3.1415926}

这很好，因为我们可以使用它来访问属性而无需真正访问它们：

>>> import library1
>>> library1.__dict__['a'] = 'never gonna run around and desert you'
>>> library1.a
'never gonna run around and desert you'
>>> library1.__dict__['this_variable_wasnt_even_defined'] = 'never gonna make you cry'
>>> library1.this_variable_wasnt_even_defined
'never gonna make you cry'

我们不想覆盖任何魔法（以两个下划线开头和结尾）属性，所以：

>>> def is_magic(name: str) -> bool:
...     return name[0] == '_' and name[1] == '_' and name[-1] == '_' and name[-2] == '_'

>>> is_magic('not_very_magic_variable')
False
>>> is_magic('__name__')
True
>>> is_magic('__init__')
True

我们也不想覆盖任何内置函数：

>>> def is_builtin(obj: object) -> bool:
...     builtin_type = type(print)
...     return obj.__class__ is builtin_type
... 

>>> is_builtin(print)
True
>>> is_builtin(open)
True

这就是一切汇集的地方。

我们使用 library3 中的值覆盖 library1 的 __dict__。

>>> from utils import is_builtin, is_magic
>>> import library1
>>> import overwrite
>>> 
>>> for key, value in overwrite.__dict__.items():
...     if is_magic(key):
...         continue
...     if is_builtin(value):
...         continue
...     # otherwise, we have something to overwrite
...     library1.__dict__[key] = value
...     print(f'I have overwritten {key} with {value}')
... 
I have overwritten var1 with -9999
I have overwritten var2 with never gonna let you down
I have overwritten a with 2.71828

可以看到library1已经被覆盖了：

# ...
>>> library1.var1
-9999
>>> library1.var2
'never gonna let you down'
>>> library1.a
2.71828

如何替换导入库中的导入？

How to replace imports in imported library?

python

python-module

python-3.x

python-importlib

警告：此方法非常 hacky，你可能可能会破坏东西。