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Nov 6, 2020
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bpo-42179: Doc/tutorial: Remove mention of __cause__ #23162

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bpo-37826: Doc/tutorial: Remove mention to __cause__
methane Nov 5, 2020
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methane Nov 5, 2020
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methane Nov 5, 2020
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15 changes: 8 additions & 7 deletions Doc/tutorial/errors.rst
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Expand Up @@ -273,10 +273,10 @@ 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 ether exception instance or None.
raise RuntimeError from exc

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

Expand All @@ -299,10 +299,9 @@ This can be useful when you are transforming exceptions. For example::
File "<stdin>", line 4, in <module>
RuntimeError

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
exception handler or :keyword:`finally` section. Exception chaining can be
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@merwok merwok Nov 5, 2020 •
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What do you think of adding: an exception handler (an :keyboard:`except` block)

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@willingc willingc Nov 5, 2020 •
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Or possibly a :keyboard: `try` block's exception handler

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@merwok merwok Nov 5, 2020

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I used a parenthetical on purpose to signify that «exception handler» == «except block» (I wrote try block by mistaked at first).
Otherwise it could be confusing what an exception handler is (is it a function you call in except? is it excepthook?)

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@methane methane Nov 5, 2020 •
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We already use :keyword:`finally` section.
How about just :keyword:`except` or :keyword:`finally` section for consistency?

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:

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