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Posted to dev@qpid.apache.org by "Jiri Daněk (Jira)" <ji...@apache.org> on 2023/04/10 17:19:00 UTC
[jira] [Resolved] (QPID-8632) [python client] Circular imports in mllib and qpid.connection, qpid.delegates
[ https://issues.apache.org/jira/browse/QPID-8632?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jiri Daněk resolved QPID-8632.
------------------------------
Fix Version/s: qpid-python-1.38.0
Assignee: Jiri Daněk
Resolution: Fixed
> [python client] Circular imports in mllib and qpid.connection, qpid.delegates
> -----------------------------------------------------------------------------
>
> Key: QPID-8632
> URL: https://issues.apache.org/jira/browse/QPID-8632
> Project: Qpid
> Issue Type: Bug
> Components: Python Client
> Affects Versions: qpid-python-1.38.0
> Reporter: Jiri Daněk
> Assignee: Jiri Daněk
> Priority: Blocker
> Fix For: qpid-python-1.38.0
>
>
> Circular imports in Python actually do work, and break only when one makes a change that trips this potential minefield. One such change is Python 2/3 compatibility.
> What triggers the problem is the situation when two modules import each other, _and_ the other module needs to be evaluated for the first import (when evaluating the first module) to complete. See https://stackoverflow.com/questions/744373/what-happens-when-using-mutual-or-circular-cyclic-imports for discussion and examples.
> Picking solution that is compatible with Python 2 as well as Python 3 in the future (QPID-8631) is tricky.
> {noformat}
> Traceback (most recent call last):
> File "./qpid-python-test", line 29, in <module>
> from qpid.harness import Skipped
> File "/home/runner/work/qpid-python/qpid-python/qpid/__init__.py", line 20, in <module>
> from . import connection
> File "/home/runner/work/qpid-python/qpid-python/qpid/connection.py", line 29, in <module>
> from . import delegates
> File "/home/runner/work/qpid-python/qpid-python/qpid/delegates.py", line 21, in <module>
> from . import connection, session
> ImportError: cannot import name connection
> {noformat}
> {noformat}
> Traceback (most recent call last):
> File "./qpid-python-test", line 30, in <module>
> from qpid.harness import Skipped
> File "/home/runner/work/qpid-python/qpid-python/qpid/__init__.py", line 21, in <module>
> from . import connection
> File "/home/runner/work/qpid-python/qpid-python/qpid/connection.py", line 21, in <module>
> from . import datatypes, session
> File "/home/runner/work/qpid-python/qpid-python/qpid/session.py", line 22, in <module>
> from .generator import command_invoker
> File "/home/runner/work/qpid-python/qpid-python/qpid/generator.py", line 23, in <module>
> from .ops import *
> File "/home/runner/work/qpid-python/qpid-python/qpid/ops.py", line 21, in <module>
> import os, mllib, sys
> File "/home/runner/work/qpid-python/qpid-python/mllib/__init__.py", line 27, in <module>
> from . import dom, transforms, parsers
> File "/home/runner/work/qpid-python/qpid-python/mllib/dom.py", line 34, in <module>
> from . import transforms
> File "/home/runner/work/qpid-python/qpid-python/mllib/transforms.py", line 25, in <module>
> from . import dom
> ImportError: cannot import name dom
> {noformat}
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