-----Original Message-----
From: python-list-bounces+ramit.prasad=jpmorgan....@python.org
[mailto:python-list-bounces+ramit.prasad=jpmorgan....@python.org] On Behalf Of
Jack Bates
Sent: Tuesday, September 13, 2011 5:28 PM
To: python-list@python.org
Subject: ImportError: cannot import name dns
Why is the following ImportError raised?
$ ./test
Traceback (most recent call last):
File "./test", line 3, in <module>
from foo import dns
File "/home/jablko/foo/dns.py", line 1, in <module>
from foo import udp
File "/home/jablko/foo/udp.py", line 1, in <module>
from foo import dns
ImportError: cannot import name dns
$
I reproduce this error with the following four files and five lines:
== foo/dns.py ==
from foo import udp
== foo/udp.py ==
from foo import dns
== foo/__init__.py ==
(empty)
== test ==
#!/usr/bin/env python
from foo import dns
===========================================================================
It is a circular dependency. Dns will try to import udp which will in turn
import dns (again) in an endless cycle; instead an ImportError is raised.
Circular dependency is a Bad Thing.
Ramit
Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
712 Main Street | Houston, TX 77002
work phone: 713 - 216 - 5423
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