[Python-Dev] New poll about a macro for safe reference replacing

[Steve Dower]

Was Py_MOVEREF (or MOVE_REF) ever suggested?

Those are valid objections, and now they're raised I remember them from last time. But I don't think they're a huge concern - setting a ref count directly doesn't seem useful anyway, and the compiler/IDE will let you know pretty quick if you put an integer vs a PyObject* there.

Cheers,
Steve

Top-posted from my Windows Phone

-----Original Message-----
From: "Nick Coghlan" <ncoghlan at gmail.com>
Sent: ‎12/‎22/‎2015 2:39
To: "Serhiy Storchaka" <storchaka at gmail.com>
Cc: "python-dev at python.org" <python-dev at python.org>
Subject: Re: [Python-Dev] New poll about a macro for safe reference replacing

On 21 December 2015 at 23:46, Serhiy Storchaka <storchaka at gmail.com> wrote:
> On 16.12.15 16:12, Serhiy Storchaka wrote:
>>
>> Please put your vote (a floating number from -1 to 1 including) for
>> every of proposed name. You also can propose new name.
>
>
> Thank you all for your votes.
>
> Results of the poll:
>
> Py_SETREF:  +5 = +5 (Victor, Steve, Yury, Brett, Nick) +0 (Ryan, Martin)
>
> Py_REPLACE_REF:  +2.5 = +2.5 (Ryan, Victor, Steve, Martin) -0 (Nick)
>
> Py_REPLACE: +0 = +1 (Martin) -1 (Ryan) +0 (Nick)
>
> Py_RESET:  0 = +1 (Ryan) -1 (Martin)
>
> Py_DECREF_REPLACE: -2 = +1 (Ryan, Martin) -3 (Victor, Steve, Nick)
>
> Py_SET_POINTER, Py_SET_ATTR: -5 (Ryan, Victor, Steve, Martin, Nick)
>
> Therefore Py_SETREF is the winner.
>
> But I want also to remember objections against it formulated in previous
> discussion.
>
> 1) By analogy with Py_INCREF and Py_DECREF that increment and decrement the
> reference counter of the object, Py_SETREF looks as it *sets* the reference
> counter of the object.
>
> 2) By analogy with PyList_SET_ITEM, PyTuple_SET_ITEM, PyCell_SET, etc, it is
> not expected that Py_SETREF decrement the refcounter of the old value before
> overwriting it.

Avoiding those misleading associations is a good argument in favour of
Py_REPLACE over Py_SETREF - they didn't occur to me before casting my
votes, and I can definitely see them causing confusion in the future.

So perhaps the combination that makes the most sense is to add
Py_REPLACE (uses Py_DECREF on destination) & Py_XREPLACE (uses
Py_XDECREF on destination) to the existing Py_CLEAR?

Regards,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia
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