52 lines
1.6 KiB
ReStructuredText
52 lines
1.6 KiB
ReStructuredText
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.. -*- coding: utf-8 -*-
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.. _OfflineIMAP: https://github.com/OfflineIMAP/offlineimap
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.. _OLI_git_repo: git://github.com/OfflineIMAP/offlineimap.git
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=================================
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Coding guidelines for OfflineIMAP
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=================================
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.. contents::
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.. .. sectnum::
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This document contains assorted guidelines for programmers that want
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to hack OfflineIMAP.
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------------------
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Exception handling
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------------------
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OfflineIMAP on many occasions re-raises various exceptions and often
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changes exception type to `OfflineImapError`. This is not a problem
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per se, but you must always remember that we need to preserve original
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tracebacks. This is not hard if you follow these simple rules.
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For re-raising original exceptions, just use::
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raise
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from inside your exception handling code.
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If you need to change exception type, or its argument, or whatever,
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use this three-argument form::
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raise YourExceptionClass(argum, ents), None, sys.exc_info()[2]
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In this form, you're creating an instance of new exception, so ``raise``
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will deduce its ``type`` and ``value`` parameters from the first argument,
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thus the second expression passed to ``raise`` is always ``None``.
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And the third one is the traceback object obtained from the thread-safe
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``exc_info()`` function.
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In fact, if you hadn't already imported the whole ``sys`` module, it will
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be better to import just ``exc_info()``::
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from sys import exc_info
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and raise like this::
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raise YourExceptionClass(argum, ents), None, exc_info()[2]
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since this is the historically-preferred style in the OfflineIMAP code.
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