Python 使用importlib.util检查库时出错

我试图使用importlib库来验证是否在执行Python 3.5.2中脚本的计算机上安装了nmap库

我试图使用importlib.util.find_spec（“nmap”）但收到以下错误

>>> import importlib
>>> importlib.util.find_spec("nmap")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'importlib' has no attribute 'util'

试试这个：

from importlib import util
util.find_spec("nmap")

我打算调查，但老实说，我不知道为什么一个有效，另一个无效。此外，请观看以下互动课程：

>>> import importlib
>>> importlib.util
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'importlib' has no attribute 'util'
>>> from importlib import util
>>> util
<module 'importlib.util' from '/usr/lib/python3.5/importlib/util.py'>
>>> importlib.util
<module 'importlib.util' from '/usr/lib/python3.5/importlib/util.py'>

因此，它可能是

importlib

所特有的

更新#3 正如@kfb在评论中指出的，它似乎确实与

importlib

有关。请参阅下面的评论：

importlib/util.py

确实导入了

importlib.\u bootstrap

，因此我假设这是真实的。如果我的理解是正确的，当您执行导入导入导入lib时，子模块将被初始化，但不会为您导入的导入导入导入lib模块对象初始化。此时，如果执行

dir（importlib）

操作，将不会看到

util

。有趣的是，在您尝试访问

importlib.util

并获得

AttributeError

后，

util

（以及其他子模块）将被加载/初始化，现在您可以访问

importlib.util

>>> import importlib
>>> dir(importlib)
['_RELOADING', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__import__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '_bootstrap', '_bootstrap_external', '_imp', '_r_long', '_w_long', 'find_loader', 'import_module', 'invalidate_caches', 'reload', 'sys', 'types', 'warnings']
>>> importlib.util
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'importlib' has no attribute 'util'
>>> importlib.util
<module 'importlib.util' from '/usr/lib/python3.5/importlib/util.py'>
>>> dir(importlib)
['_RELOADING', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__import__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '_bootstrap', '_bootstrap_external', '_imp', '_r_long', '_w_long', 'abc', 'find_loader', 'import_module', 'invalidate_caches', 'machinery', 'reload', 'sys', 'types', 'util', 'warnings']

导入导入库 >>>处长（进口管制） “UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU_模块“，”使_缓存无效“，”重新加载“，”系统“，”类型“，”警告“] >>>importlib.util 回溯（最近一次呼叫最后一次）： 文件“”，第1行，在 AttributeError:模块“importlib”没有属性“util” >>>importlib.util >>>处长（进口管制） “UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU“，”导入模块“，”使缓存无效“，”机械“，”重新加载“，”系统“，”类型“，”util“，”警告“]

---

可能是在说明显而易见的问题，但您在尝试使用

importlib

之前是否执行了

importlib

？@ldjaw是的，很抱歉在问题中没有说明这一点。为清晰起见，编辑了问题。@idjaw刚刚尝试，没有爱情：（相同的错误消息。我尝试了这个，它说util不存在，很漂亮-看起来像是这样！这个没有返回任何东西，我理解这意味着它工作正常。谢谢！@DKNUCKLES，太好了！不确定为什么它不以其他方式工作…在我更新的答案中看到奇怪的交互会话。谢谢为此。我希望我能不止一次地为你的帮助投票。我已经能够拼凑出一些对我有用的东西，我将在我的问题中发布。看起来是这样。@DKNUCKLES没问题！当像你这样有趣的问题出现时，我很高兴。这对提问者和提问者来说都是一个学习的好机会回答者！

>>> import datetime
>>> datetime
<module 'datetime' from '/usr/lib/python3.5/datetime.py'>
>>> datetime.datetime
<class 'datetime.datetime'>

>>> import urllib
>>> urllib
<module 'urllib' from '/usr/lib/python3.5/urllib/__init__.py'>
>>> urllib.error
<module 'urllib.error' from '/usr/lib/python3.5/urllib/error.py'>

# Until bootstrapping is complete, DO NOT import any modules that attempt
# to import importlib._bootstrap (directly or indirectly). Since this
# partially initialised package would be present in sys.modules, those
# modules would get an uninitialised copy of the source version, instead
# of a fully initialised version (either the frozen one or the one
# initialised below if the frozen one is not available).

>>> import importlib
>>> dir(importlib)
['_RELOADING', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__import__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '_bootstrap', '_bootstrap_external', '_imp', '_r_long', '_w_long', 'find_loader', 'import_module', 'invalidate_caches', 'reload', 'sys', 'types', 'warnings']
>>> importlib.util
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'importlib' has no attribute 'util'
>>> importlib.util
<module 'importlib.util' from '/usr/lib/python3.5/importlib/util.py'>
>>> dir(importlib)
['_RELOADING', '__all__', '__builtins__', '__cached__', '__doc__', '__file__', '__import__', '__loader__', '__name__', '__package__', '__path__', '__spec__', '_bootstrap', '_bootstrap_external', '_imp', '_r_long', '_w_long', 'abc', 'find_loader', 'import_module', 'invalidate_caches', 'machinery', 'reload', 'sys', 'types', 'util', 'warnings']