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Subject: Re: [PATCH] selftests/tpm2: Change exception handling to be Python 3
 compatible
From:   Ezra Buehler <ezra@easyb.ch>
In-Reply-To: <20200413180440.GA10917@linux.intel.com>
Date:   Tue, 14 Apr 2020 07:45:33 +0200
Cc:     Shuah Khan <shuah@kernel.org>, linux-kselftest@vger.kernel.org,
        linux-integrity@vger.kernel.org,
        Tadeusz Struk <tadeusz.struk@intel.com>,
        open list <linux-kernel@vger.kernel.org>
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Message-Id: <D670A3F7-6FE2-4A07-8251-680C2ED27764@easyb.ch>
References: <20200412143656.72955-1-jarkko.sakkinen@linux.intel.com>
 <1FE03B4F-C42C-4B5F-A4B5-8169705911FA@easyb.ch>
 <20200412170719.GA324408@linux.intel.com>
 <531D50E8-E8FC-402E-9226-6000E8B6E960@easyb.ch>
 <20200413180440.GA10917@linux.intel.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Hi Jarkko,

On 13 Apr 2020, at 20:04, Jarkko Sakkinen =
<jarkko.sakkinen@linux.intel.com> wrote:
>=20
> On Mon, Apr 13, 2020 at 07:02:20AM +0200, Ezra Buehler wrote:
>> Hi Jarkko,
>>=20
>> On 12 Apr 2020, at 19:07, Jarkko Sakkinen =
<jarkko.sakkinen@linux.intel.com> wrote:
>>>=20
>>> On Sun, Apr 12, 2020 at 05:02:27PM +0200, Ezra Buehler wrote:
>>>> Hi Jarkkon,
>>>>=20
>>>>> On 12 Apr 2020, at 16:36, Jarkko Sakkinen =
<jarkko.sakkinen@linux.intel.com> wrote:
>>>>> +        except ProtocolError(e):
>>>>=20
>>>> Should this not be
>>>>=20
>>>>       except ProtocolError as e:
>>>=20
>>> Unless there is a functional difference, does it matter?
>>>=20
>>> /Jarkko
>>=20
>> Well, your patch confuses me a lot. It looks to me like you are =
passing
>> the undefined `e` variable to the constructor.
>>=20
>> When I run flake8 on it I get following error (among others):
>>=20
>>    F821 undefined name 'e'
>=20
> I don't know what flake8 is.

https://flake8.pycqa.org/en/latest/

>> What I suggested is the standard syntax:
>> https://docs.python.org/3/tutorial/errors.html
>=20
> It passed the Python 3 interpreter.

That is because it is technically valid syntax.

>> Did you test this? You should get an error as soon as an exception
>> occurs.
>=20
> Yes. Interpreter did not complain. I did not know that the language
> is broken that way that you have to exercise the code path to get
> a syntax error.

That is due to the dynamic nature of Python. You won=E2=80=99t get a =
syntax
error. You will get an exception:

    NameError: name 'e' is not defined

Python has to assume that `e` might be defined at runtime. However,
style checkers will complain.

>=20
> /Jarkko

Cheers,
Ezra.