isinstance(url, URL) returns False for BaseURL

[Gallaecio]

Specifically, this evaluates to false: isinstance(URL('http://example.com').with_fragment(None), URL)

I tested it as follows:

[adrian@chakra yarl]$ python3 -m venv venv
[adrian@chakra yarl]$ . venv/bin/activate
(venv) [adrian@chakra yarl]$ pip install yarl
Collecting yarl
  Downloading yarl-0.9.5-cp35-cp35m-manylinux1_x86_64.whl (165kB)
    100% |████████████████████████████████| 174kB 2.1MB/s 
Collecting multidict>=2.0 (from yarl)
  Downloading multidict-2.1.4-cp35-cp35m-manylinux1_x86_64.whl (357kB)
    100% |████████████████████████████████| 358kB 746kB/s 
Installing collected packages: multidict, yarl
Successfully installed multidict-2.1.4 yarl-0.9.5
You are using pip version 8.1.1, however version 9.0.1 is available.
You should consider upgrading via the 'pip install --upgrade pip' command.
(venv) [adrian@chakra yarl]$ echo "from yarl import URL" >> test.py
(venv) [adrian@chakra yarl]$ echo "print(isinstance(URL('http://example.com').with_fragment(None), URL))" >> test.py
(venv) [adrian@chakra yarl]$ python test.py 
False
(venv) [adrian@chakra yarl]$ 

I realize that there are many chances that I am the one doing something wrong here, as I found this issue debugging an exception raised by trivial aiohttp code.

If this is as expected, I will proceed to report the issue downstream to aiohttp.

[hellysmile]

I have same problems

[Gallaecio]

This happens in 0.9.4 and 0.9.5. Downgrading to 0.9.3 fixes it for me.

[arthurdarcet]

@fafhrd91 could you look at this? This breaks all HTTP requests made with the aiohttp client aio-libs/aiohttp#1632

I'm not sure why this BaseURL class was introduced, but returning something that isn't an instance of X in X.__new__ looks like a very bad idea to me. Could you revert this?

[fafhrd91]

Yes, reverted