[3.8] bpo-42669: Document that except rejects nested tuples (GH-23822)
#23871
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In Python 2, it was possible to use `except` with a nested tuple, and occasionally natural. For example, `zope.formlib.interfaces.InputErrors` is a tuple of several exception classes, and one might reasonably think to do something like this:
try:
self.getInputValue()
return True
except (InputErrors, SomethingElse):
return False
As of Python 3.0, this raises `TypeError: catching classes that do not inherit from BaseException is not allowed` instead: one must instead either break it up into multiple `except` clauses or flatten the tuple. However, the reference documentation was never updated to match this new restriction. Make it clear that the definition is no longer recursive.
Automerge-Triggered-By: GH:ericvsmith
(cherry picked from commit c95f8bc)
Co-authored-by: Colin Watson <[email protected]>
|
@cjwatson: Status check is done, and it's a success ✅ . |
|
@cjwatson: Status check is done, and it's a success ✅ . |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In Python 2, it was possible to use
exceptwith a nested tuple, and occasionally natural. For example,zope.formlib.interfaces.InputErrorsis a tuple of several exception classes, and one might reasonably think to do something like this:As of Python 3.0, this raises
TypeError: catching classes that do not inherit from BaseException is not allowedinstead: one must instead either break it up into multipleexceptclauses or flatten the tuple. However, the reference documentation was never updated to match this new restriction. Make it clear that the definition is no longer recursive.Automerge-Triggered-By: GH:ericvsmith
(cherry picked from commit c95f8bc)
Co-authored-by: Colin Watson [email protected]
https://bugs.python.org/issue42669