bitdancer
commented
12 years ago As discussed in my email to python-dev, I'm planning to add the new header parsing to Python 3.3 as a provisional extension, by adding a (set) of policies that are clearly marked provisional in the documentation. In order for this to work, I first need to make certain enhancements to the Policy framework that I previously committed to default.
When reviewing the patch, please start with the 'architecture.rst' file in the Lib/email directory, which provides an overview of the changes and the plan.
The primary changes are to add some new policy hooks that feedparser, message, and generator call. These hooks are then implemented on the renamed default policy (now called 'compat32') in such a way as to replicate the behavior of Python 3.2. The other significant change is that Message objects now have a policy. In order to accommodate this, this patch adds 'policy propagation' logic. That is, if you pass a policy to feedparser, then all the Message objects it creates get that policy. And when you flatten a message with a Generator, it uses the policy attached to the message unless you explicitly override it.
I also factored policy into _basepolicy.py and policy.py. This doesn't mean much for this patch, but when the new policies land they go in policy.py, while the default policy is imported from _policybase. This means that if a Python 3.3 program does not explicitly use a policy, it will not import any of the new code.
The remaining changes in the patch are some test reorganization. Since the goal is now 100% backward compatibility with Python 3.2 (including bugs in some cases), the patch removes some tests that were previously added to test.test_email.test_email and puts them into module specific test files (test_generator, test_parser, test_policy). Additional tests are also added.
The end result of the test refactoring is that if you diff test_email.py after this patch against the 3.2 test_email.py, you should find a few places where the scaffolding is changed and the addition of some tests for bug fixes in the 3.2 code. Otherwise the tests should be identical to 3.2, with all the policy related tests moving into test_policy.
The longer term plan for this is to replicate all of the test_email.py tests in appropriate module-specific test files (I've already marked a few such tests that got replicated in test_policy). By the time we get to Python4 the plan is for all the tests to be replicated, so that we can at that point drop compat32 by removing the policy and the test_email.py test file, as well as the code that will be at that point obsolete.
The primary review here should be to make sure I am in fact producing 100% backward compatibility. Any other review comments will be welcome, of course.
PS: I also changed the 'must_be_7bit' policy control, whose name I never liked, to be 'cte_type', which can be '7bit' or '8bit'. As noted in the architecture.rst file, the extra motivation for this is that there will eventually be a 'cte_type=unicode' which will support unicode display of formatted messages and, perhaps even more important, rfc 5335.
merwok
1762cc99-3127-4a62-9baf-30c3d0f51ef7
Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.
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GitHub fields: ```python assignee = 'https://github.com/bitdancer' closed_at =
created_at =
labels = ['type-feature', 'expert-email']
title = 'Enhance Policy framework in preparation for adding email6 policies as provisional'
updated_at =
user = 'https://github.com/bitdancer'
```
bugs.python.org fields:
```python
activity =
actor = 'python-dev'
assignee = 'r.david.murray'
closed = True
closed_date =
closer = 'r.david.murray'
components = ['email']
creation =
creator = 'r.david.murray'
dependencies = []
files = ['25467']
hgrepos = ['121']
issue_num = 14731
keywords = ['patch']
message_count = 8.0
messages = ['160015', '161228', '161229', '161231', '161601', '161602', '161626', '161639']
nosy_count = 5.0
nosy_names = ['barry', 'eric.araujo', 'r.david.murray', 'python-dev', 'hynek']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'patch review'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue14731'
versions = ['Python 3.3']
```