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Fix types.coroutine to accept objects from Cython #68504
Description
| BPO | 24316 |
|---|---|
| Nosy | @gvanrossum, @ncoghlan, @scoder, @1st1 |
| Dependencies | |
| Files |
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 = 'https://github.com/1st1'
closed_at = <Date 2015-05-29.20:21:09.464>
created_at = <Date 2015-05-28.16:31:52.508>
labels = ['library']
title = 'Fix types.coroutine to accept objects from Cython'
updated_at = <Date 2015-05-29.21:11:28.466>
user = 'https://github.com/1st1'bugs.python.org fields:
activity = <Date 2015-05-29.21:11:28.466>
actor = 'yselivanov'
assignee = 'yselivanov'
closed = True
closed_date = <Date 2015-05-29.20:21:09.464>
closer = 'yselivanov'
components = ['Library (Lib)']
creation = <Date 2015-05-28.16:31:52.508>
creator = 'yselivanov'
dependencies = ['24315']
files = ['39536', '39548', '39551', '39555', '39556', '39557']
hgrepos = []
issue_num = 24316
keywords = ['patch']
message_count = 14.0
messages = ['244315', '244373', '244386', '244391', '244393', '244394', '244399', '244406', '244408', '244409', '244412', '244413', '244414', '244419']
nosy_count = 5.0
nosy_names = ['gvanrossum', 'ncoghlan', 'scoder', 'python-dev', 'yselivanov']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue24316'
versions = ['Python 3.5', 'Python 3.6']
Activity
1st1 commentedon May 28, 2015
Stefan,
This patch should solve the problem with types.coroutine accepting only pure python generator functions.
The approach is, however, slightly different from what you've proposed. Instead of having a wrapper class (delegating .throw, .send etc to a wrapped object), we now simply check if the returned value of the wrapped function is an instance of collections.abc.Coroutine. bpo-24315 enables duck typing for coroutines, so if a cython-based coroutine implements all coroutine abstract methods, it will automatically pass types.coroutine.
python-dev commentedon May 29, 2015
New changeset 7356f71fb0a4 by Yury Selivanov in branch '3.5':
bpo-24316: Fix types.coroutine() to accept objects from Cython
https://hg.python.org/cpython/rev/7356f71fb0a4
New changeset 748c55375225 by Yury Selivanov in branch 'default':
bpo-24316: Fix types.coroutine() to accept objects from Cython
https://hg.python.org/cpython/rev/748c55375225
scoder commentedon May 29, 2015
I just noticed that I hadn't used the real "types.coroutine" in my Py3.5 tests when reporting back in bpo-24017. When I pass a Cython generator through it, I get
This is actually obvious, given that the sole purpose of the decorator is to turn something that is a Generator and *not* a Coroutine into something that is a Coroutine, as a means for the user to say "but I know better". So checking for the return value being a Coroutine is wrong. Instead, it should check that it's a Generator and if it's not an Awaitable, wrap it as a self-returning Awaitable. That's more or less what my proposed implementation in bpo-24017 did:
1st1 commentedon May 29, 2015
Please test thoroughly the attached patch.
scoder commentedon May 29, 2015
One failing test in "test_coroutines": test_func_5. The reason is that the GeneratorWrapper is not iterable (and there is no reason it shouldn't be, given that it wraps a Generator). That was my fault, I had already added an __iter__ method but didn't copy it in my previous message. Adding it as follows fixes the test for me:
Alternatively, "__iter__ = __await__" would do the same.
scoder commentedon May 29, 2015
BTW, it's not only for compiled generators but also for normal Python functions that construct Python generators internally and return them, or that delegate the generator creation in some way. With this change, it's enough to decorate the constructor function and not each of the potential generators that it returns.
1st1 commentedon May 29, 2015
Please test the attached patch.
You're right, that's why I used "primarily" word in that comment ;)
types.coroutine() is only used by asyncio.coroutine() so far, and returning generator objects from "factory" functions isn't a very common pattern in asyncio.
1st1 commentedon May 29, 2015
Updated patch. Wrapper now proxies gi_code, gi_running and gi_frame
scoder commentedon May 29, 2015
Ok, now the problem with *this* patch is that __iter__ and __await__ are special methods that are being looked up on the type, not the instance. Similarly __next__, I think, as it also has its own (type) slot. But I think you're right that __next__ is also needed here.
I'm attaching a patch that works for me.
1st1 commentedon May 29, 2015
Looks like we were working in parallel ;) I've incorporated your changes. Please look at the new patch (hopefully this one is final)
scoder commentedon May 29, 2015
Your latest patch works for me.
python-dev commentedon May 29, 2015
New changeset 8080b53342e8 by Yury Selivanov in branch '3.5':
bpo-24316: Wrap gen objects returned from callables in types.coroutine
https://hg.python.org/cpython/rev/8080b53342e8
New changeset c0434ef75177 by Yury Selivanov in branch 'default':
bpo-24316: Wrap gen objects returned from callables in types.coroutine
https://hg.python.org/cpython/rev/c0434ef75177
1st1 commentedon May 29, 2015
Committed. Thanks, Stefan!
1st1 commentedon May 29, 2015
Stefan, please take a look at this issue bpo-24325 too.