Re: [Qemu-devel] [PATCH 5/9] iotests: Different iterator behavior in Python 3

[Max Reitz <mreitz@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 2150 bytes --]

On 16.10.18 00:39, Cleber Rosa wrote:
> 
> 
> On 10/15/18 10:14 AM, Max Reitz wrote:
>> In Python 3, several functions now return iterators instead of lists.
>> This includes range(), items(), map(), and filter().  This means that if
>> we really want a list, we have to wrap those instances with list().  On
>> the other hand, sometimes we do just want an iterator, in which case we
>> have sometimes used xrange() and iteritems() which no longer exist in
>> Python 3.  Just change these calls to be range() and items(), which
>> costs a bit of performance in Python 2, but will do the right thing in
>> Python 3 (which is what is important).
>>
>> In one instance, we only wanted the first instance of the result of a
>> filter() call.  Instead of using next(filter()) which would work only in
>> Python 3, or list(filter())[0] which would work everywhere but is a bit
>> weird, this instance is changed to a single-line for with next() wrapped
>> around, which works both in 2.7 and 3.
>>
>> Signed-off-by: Max Reitz <mreitz@redhat.com>
>> ---
>>  tests/qemu-iotests/044 | 12 ++++++------
>>  tests/qemu-iotests/056 |  2 +-
>>  tests/qemu-iotests/065 |  4 ++--
>>  tests/qemu-iotests/124 |  4 ++--
>>  tests/qemu-iotests/139 |  2 +-
>>  tests/qemu-iotests/163 |  6 +++---
>>  6 files changed, 15 insertions(+), 15 deletions(-)
>>
> 
> You have 2 files here which use xrange (which is a manageable size, and
> whose occurrences involve a moderate size of items) to also consider:
> 
> if sys.version_info.major == 2:
>    range = xrange

I don't think it's necessary, but it's so easy to grep for
"sys.version_info" once we want to completely switch to Python 3 that I
can't find good arguments against it. O:-)

Max

> Defaulting to the Python 3 names, but behaving the same across Python 2
> and 3.
> 
> To do the same for dict.iteritems() => dict.items() requires a lot more
> code, so I'd stay away from it for now.  Also, it looks like most of
> those dicts are small in size (**kwargs and the like).
> 
> Other than that suggestion,
> 
> Reviewed-by: Cleber Rosa <crosa@redhat.com>
> 



[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 488 bytes --]