如果从源目录导入，则捕获 python 'ImportError'
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Catch python 'ImportError' if import from source directory
提问by Julian
When one tries to import a module foowhile being in the source directory, one gets an rather confusing ImportErrormessage: ImportError: No module named foo.
当foo在源目录中尝试导入模块时，会收到一条相当混乱的ImportError消息：ImportError: No module named foo.
How can I easily catch this case and return a more informative message, e.g. 'Please do not load module foo from the source directory'?
我怎样才能轻松地捕捉到这种情况并返回一条信息更丰富的消息，例如“请不要从源目录加载模块 foo”？
Having the __init__.py, I would start with:
有了__init__.py，我会开始：
try:
from _foo import *
except ImportError:
## check whether in the source directory...
So I would like to distinguish the different causes for an ImportError(e.g. because a module named foois not installed at all), and detect the case in which the setup.pyis located in the current directory. What would be a elegant way of doing this?
所以我想区分不同的原因ImportError（例如因为foo根本没有安装一个名为的模块），并检测setup.py位于当前目录中的情况。这样做的优雅方式是什么？
采纳答案by isedev
ImportError: No module named fooactually means the module foo.pyor package foo/__init__.pycould not be found in any of the directories in the search path (sys.pathlist).
ImportError: No module named foo实际上意味着在搜索路径（列表）的任何目录中都找不到模块foo.py或包。foo/__init__.pysys.path
Since sys.pathusually contains .(the current directory), that's probably what you meant by being in the source directory. You are in the top-level directory of package foo(where the __init__.pyfile is) so obviously you can't find foo/__init__.py.
由于sys.path通常包含.（当前目录），这可能就是您在源目录中的意思。您位于包的顶级目录foo（__init__.py文件所在的位置），因此显然您找不到foo/__init__.py.
Finally, you've answered your own question, more or less:
最后，您或多或少地回答了自己的问题：
try:
from _foo import *
except ImportError:
raise ImportError('<any message you want here>')
Alternatively, you could check the contents of sys.path, the current directory and, if known, the expected package directory and produce an even detailed and context-aware message.
或者，您可以检查 的内容sys.path、当前目录以及（如果知道）预期的包目录，并生成甚至详细且上下文感知的消息。
Or add ..to the PYTHONPATHenvironment variable (on Unix) to allow you to run from your source directory. Might even work on Windows, but I wouldn't know.
或者添加..到PYTHONPATH环境变量（在 Unix 上）以允许您从源目录运行。甚至可能在 Windows 上工作，但我不知道。
