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Re: [Qemu-block] [Qemu-devel] [PATCH] iotests: handle TypeError for Pyth
From: |
Andrey Shinkevich |
Subject: |
Re: [Qemu-block] [Qemu-devel] [PATCH] iotests: handle TypeError for Python3 in test 242 |
Date: |
Fri, 22 Feb 2019 09:48:03 +0000 |
On 22/02/2019 03:17, Cleber Rosa wrote:
>
>
> On 2/18/19 4:25 PM, Philippe Mathieu-Daudé wrote:
>> On 2/18/19 9:05 PM, Eric Blake wrote:
>>> [adding Eduardo for some python 2-vs-3 advice]
>>
>> And Cleber.
>>
>>>
>>> On 2/18/19 1:59 PM, Andrey Shinkevich wrote:
>>>> To write one byte to disk, Python2 may use 'chr' type.
>>>> In Python3, conversion to 'byte' type is required.
>>>>
>>>> Signed-off-by: Andrey Shinkevich <address@hidden>
>>>> ---
>>>> tests/qemu-iotests/242 | 9 +++++++--
>>>> 1 file changed, 7 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/tests/qemu-iotests/242 b/tests/qemu-iotests/242
>>>> index 16c65ed..6b1f7b8 100755
>>>> --- a/tests/qemu-iotests/242
>>>> +++ b/tests/qemu-iotests/242
>>>> @@ -65,9 +65,14 @@ def toggle_flag(offset):
>>>> with open(disk, "r+b") as f:
>>>> f.seek(offset, 0)
>>>> c = f.read(1)
>>>> - toggled = chr(ord(c) ^ bitmap_flag_unknown)
>>>> + toggled = ord(c) ^ bitmap_flag_unknown
>>>> f.seek(-1, 1)
>>>> - f.write(toggled)
>>>> + try:
>>>> + # python2
>>>> + f.write(chr(toggled))
>>>> + except TypeError:
>>>> + # python3
>>>> + f.write(bytes([toggled]))
>>>
>>> Looks like it works, but I'm not enough of a python expert to know if
>>> there is a more Pythonic elegant approach.
>>>
>
> Well, there's no way around the fact that bytes in Python 3 are very
> different from bytes in Python 2 (just another name for a string).
>
> What I'd recommend here is to not base the type on the exception, but
> choose it depending on the Python version. Something like:
>
> if sys.version_info.major == 2:
> f.write(chr(toggled))
> else:
> f.write(bytes([toggled])]
>
> This is cheaper than raising/catching exceptions, it's self documenting,
> and follows the pattern on other tests.
>
> Regards,
> - Cleber.
>
Thank you very much, Cleber.
I would like to write it down as that is in iotests.py :
if sys.version_info.major >= 3:
...
>>> If someone else picks it up before my next NBD pull request,
>>> Acked-by: Eric Blake <address@hidden>
>>>
--
With the best regards,
Andrey Shinkevich