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From: Pavlos Parissis <pavlos.parissis@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: Handling exceptions with Py2 and Py3
Date: Fri, 27 May 2016 15:42:07 +0200
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From: Pavlos Parissis <pavlos.parissis@gmail.com>
To: python-list@python.org
Message-ID: <57484EAF.9060507@gmail.com>
Subject: Re: Handling exceptions with Py2 and Py3
References: <57483C86.6030304@gmail.com>
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On 27/05/2016 02:51 =CE=BC=CE=BC, Steven D'Aprano wrote:
> On Fri, 27 May 2016 10:24 pm, Pavlos Parissis wrote:
>=20
>> Hi,
>>
>> So, we have ConnectionRefusedError in Python3 but not in Python2.
>> Six module doesn't provide a wrapper about this.
>>
>> What is most efficient way to handle this situation in a try-catch blo=
ck?
>=20
> Um, could you give us a hint as to context?
>=20

The following is inside a while true loop which implements a
retry logic.

try:

    unix_socket =3D socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
    unix_socket.settimeout(0.5)
    unix_socket.connect(self.socket_file)
    unix_socket.send(six.b(command + '\n'))
    file_handle =3D unix_socket.makefile()
    data =3D file_handle.read().splitlines()
except ConnectionRefusedError:
    raised =3D SocketConnectionError(self.socket_file)
except socket.timeout:
    raised =3D SocketTimeout(socket_file=3Dself.socket_file)
except OSError as error:

    if error.errno =3D=3D 106:
        raised =3D SocketTransportError(socket_file=3Dself.socket_file)
    else:
        raised =3D error
else:
    procecess(data)
finally:
    unix_socket.close()
    if raised:
        time.sleep(self.retry_interval)


> What does Python 2 raise instead of ConnectionRefusedError? I don't kno=
w, so
> for the sake of calling it *something* I'll say it's FooError. Then if =
it
> is a simple name, you can do this:
>=20
>=20
> if sys.version < "3":
>     ConnectionRefusedError =3D FooError
>=20
> # much later
> try:
>    do_the_thing()
> except ConnectionRefusedError:
>     ...
>=20
>=20
>=20
> Or instead of checking for the version, you can check for the name:
>=20
>=20
> try:
>     from some_module import ConnectionRefusedError
> except ImportError:
>     # Must be Python 2
>     from another_module import FooError as ConnectionRefusedError
>=20
>=20
> If neither of these techniques help, please give more context and we ca=
n be
> more specific.
>=20
>=20
>=20

I will try the approach mentioned by Ben Finney as I am already checking =
'errno'.

Thanks everyone for the replies.

Cheers,
Pavlos


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