Skip to content

bpo-42179: Doc/tutorial: Remove mention of __cause__ #23162

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 3 commits into from
Nov 6, 2020
Merged

bpo-42179: Doc/tutorial: Remove mention of __cause__ #23162

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
c704d93
bpo-37826: Doc/tutorial: Remove mention to __cause__
methane Nov 5, 2020
7508f69
fixup
methane Nov 5, 2020
b43dfa6
fixup
methane Nov 5, 2020
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 10 additions & 9 deletions Doc/tutorial/errors.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -273,15 +273,15 @@ Exception Chaining
==================

The :keyword:`raise` statement allows an optional :keyword:`from` which enables
chaining exceptions by setting the ``__cause__`` attribute of the raised
exception. For example::
chaining exceptions. For example::

raise RuntimeError from OSError
# exc must be exception instance or None.
raise RuntimeError from exc

This can be useful when you are transforming exceptions. For example::

>>> def func():
... raise IOError
... raise IOError
...
>>> try:
... func()
Expand All @@ -297,12 +297,11 @@ This can be useful when you are transforming exceptions. For example::
<BLANKLINE>
Traceback (most recent call last):
File "<stdin>", line 4, in <module>
RuntimeError
RuntimeError: Failed to open database

The expression following the :keyword:`from` must be either an exception or
``None``. Exception chaining happens automatically when an exception is raised
inside an exception handler or :keyword:`finally` section. Exception chaining
can be disabled by using ``from None`` idiom:
Exception chaining happens automatically when an exception is raised inside an
:keyword:`except` or :keyword:`finally` section. Exception chaining can be
disabled by using ``from None`` idiom:

>>> try:
... open('database.sqlite')
Expand All @@ -313,6 +312,8 @@ can be disabled by using ``from None`` idiom:
File "<stdin>", line 4, in <module>
RuntimeError

For more information about chaining mechanics, see :ref:`bltin-exceptions`.


.. _tut-userexceptions:

Expand Down