PEP 341 - Unification of try/except and try/finally

[krumms]

BPO	1355913
Nosy	@gvanrossum, @birkenfeld, @ncoghlan
Files	PEP-341.patch: Patch implementing PEP 341 test_exception_variations.py: Unit test for new exception handling syntax pep-341.patch: v2 - contains code and test PEP-341.patch: v3 - fixes to a few memory leaks Neal missed PEP-341.patch: v4 - try-finally was causing memory leaks PEP-341.patch: v5 - fixes for bugs reported by Neal Norwitz, unit test updated PEP-341.patch: v6 - test-goto-cleanup. use asdl_stmt_seq_free to deallocate asdl_seq instances PEP-341.patch: v7 - fix for another bug spotted by Neal, do ... while try/except emulation instead of ugly gotos PEP-341.patch: v8 - fixes for still more leaks discovered by Neal, back to using goto :( PEP-341.patch: v9 - fixes for even more leaks discovered by Nick

^{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:

assignee = None
closed_at = <Date 2005-12-17.21:34:20.000>
created_at = <Date 2005-11-13.14:59:08.000>
labels = ['interpreter-core']
title = 'PEP 341 - Unification of try/except and try/finally'
updated_at = <Date 2005-12-17.21:34:20.000>
user = 'https://bugs.python.org/krumms'

bugs.python.org fields:

activity = <Date 2005-12-17.21:34:20.000>
actor = 'nnorwitz'
assignee = 'nnorwitz'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2005-11-13.14:59:08.000>
creator = 'krumms'
dependencies = []
files = ['6865', '6866', '6867', '6868', '6869', '6870', '6871', '6872', '6873', '6874']
hgrepos = []
issue_num = 1355913
keywords = ['patch']
message_count = 25.0
messages = ['49016', '49017', '49018', '49019', '49020', '49021', '49022', '49023', '49024', '49025', '49026', '49027', '49028', '49029', '49030', '49031', '49032', '49033', '49034', '49035', '49036', '49037', '49038', '49039', '49040']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'nnorwitz', 'georg.brandl', 'ncoghlan', 'krumms']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1355913'
versions = ['Python 2.5']

[krumms]

Attached is a patch implementing PEP-341 against HEAD
in subversion.

It includes the following changes:

1. Grammar/Grammar updated as per the PEP-2. Python/ast.c wraps try/except blocks inside
   try/finally blocks if it detects the extended syntax.

This patch is based heavily upon suggestions by Nick
Coghlan on python-dev.

[krumms]

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Attaching a unit test checking the various different types
of exception handling syntax.

[nnorwitz]

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Updated patch to correct memory leaks. Put everything in
one file. Works for me.

There needs to be doc changes done too.

[nnorwitz]

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I'm pretty sure this patch causes this problem:

python: Objects/frameobject.c:187: frame_setlineno:
Assertion `blockstack_top > 0' failed.

I'm not sure if it's just my hacked up version or the
original. Thomas, can you test your version?

[krumms]

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Further correction of memory leaks.

'finally' and 'orelse' need to be deallocated if an error
occurs in the "if (n_except > 0)" branch.

[krumms]

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Further correction of memory leaks.

'finally' and 'orelse' need to be deallocated if an error
occurs in the "if (n_except > 0)" branch.

[krumms]

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Fixed a bad assumption when parsing a try-finally. Should be
fixed now.

I'm not sure if this fixes the problem you're experiencing,
Neal. I'll have a look into it.

[krumms]

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Fix for the problem you encountered in the v5 patch, Nick.

All tests in the suite now pass for me, no assertion
failures when using --with-pydebug.

I was stupidly generating a TryFinally in every scenario.
This breaks down in the 'trace' unit test when no 'finally'
clause is present with the extended syntax. Oops.

Also added a little more error checking code and updated the
unit test to test nested exception handling.

I'm using a few goto statements in the "if (n_except > 0)"
branch to reduce duplication deallocating memory. If there's
any great objections to this feel free to yell & I'll
resubmit a patch without the use of goto.

Can you please verify this works for you, Nick?

[krumms]

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Oops - I mean Neal :)