遇到一个奇怪的问题，怀疑是 python 的 bug

[guyskk]

代码在这：
https://gist.github.com/guyskk/8ae152653220800e9b9a
被注释掉的都会报 KeyError
最后那句print(dict([(k, items[k]) for k in keys]))在 python3 会报错,python2 正常

[fy]

楼主的代码报错：

k1 = 'v1'
k2 = 'v2'

module_items = locals()
module_keys = ['k1', 'k2']
print({k: locals()[k] for k in module_keys}) # 这一句


我的测试结果（ Python 3.4 ）：

>>> print({k: [locals(), k] for k in module_keys})
{'k1': [{'.0': <list_iterator object at 0x03299E10>, 'k': 'k2'}, 'k1'], 'k2': [{'.0': <list_iterator object at 0x03299E10>, 'k': 'k2'}, 'k2']}
>>>
>>>
>>> locals()
{'k2': 'v2', '__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None, 'module_keys': ['k1', 'k2'], 'module_items': {...}, 'k1': 'v1', '__builtins__': <module 'builtins' (built-in)>, '__package__': None, '__name__': '__main__', '__doc__': None}

确实是报错了，我试着输出了 locals()

可以看到 locals() 所指代的内容不同，我猜测是生成器的实现有所不同了

[fy]

>>> print([id(locals()) for k in module_keys])
[53111664, 53111664]
>>> id(locals())
41054976

确实如此

[guyskk]

被注释掉的语句都是会报错的，我在 python2.7 和 python3.4 上都试了

[guyskk]

class A:
a = 42
b = list(a + i for i in range(10))
b = [a + i for i in range(10)]

第 1 个 b 那里会报错，第 2 个正常

好像是作用域的问题

[realityone]

参考
- http://stackoverflow.com/questions/20136955/python3-nested-list-comprehension-scope

[fy]

补充一个 Python 2.7 的：

Python 2.7.10 (default, May 23 2015, 09:40:32) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> module_keys = ['k1', 'k2']
>>>
>>> print([id(locals()) for k in module_keys])
[40479312, 40479312]
>>> id(locals())
40479312

[guyskk]

搞定了，多谢各位帮忙