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Fix types.coroutine to accept objects from Cython #68504Description
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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'] Activity1st1 commented on 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 commented on May 29, 2015 scoder commented on 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
"""
Traceback (most recent call last):
File "tests/run/test_coroutines_pep492.pyx", line 245, in test_coroutines_pep492.CoroutineTest.test_func_5 (test_coroutines_pep492.c:13445)
for el in bar():
File "/opt/python3.5/lib/python3.5/types.py", line 197, in wrapped
'non-coroutine: {!r}'.format(coro))
TypeError: callable wrapped with types.coroutine() returned non-coroutine: <generator object at 0x7f178c458898>
"""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:
class types_coroutine(object):
def __init__(self, gen):
self._gen = gen
class as_coroutine(object):
def __init__(self, gen):
self._gen = gen
self.send = gen.send
self.throw = gen.throw
self.close = gen.close
def __await__(self):
return self._gen
def __call__(self, *args, **kwargs):
return self.as_coroutine(self._gen(*args, **kwargs))1st1 commented on 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.
Please test thoroughly the attached patch. scoder commented on 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:
def __iter__(self):
return self.__wrapped__Alternatively, "__iter__ = __await__" would do the same. scoder commented on 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 commented on May 29, 2015 Please test the attached patch.
BTW, it's not only for compiled generators but also for normal Python functions that construct Python generators internally and return them
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 commented on May 29, 2015 Updated patch. Wrapper now proxies gi_code, gi_running and gi_frame scoder commented on 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 commented on May 29, 2015
I'm attaching a patch that works for me.
Looks like we were working in parallel ;) I've incorporated your changes. Please look at the new patch (hopefully this one is final) scoder commented on May 29, 2015 Your latest patch works for me. python-dev commented on May 29, 2015 1st1 commented on May 29, 2015 Committed. Thanks, Stefan! 1st1 commented on May 29, 2015 Stefan, please take a look at this issue bpo-24325 too.
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