[Development] QList

Konstantin Tokarev annulen at yandex.ru
Wed May 24 15:24:48 CEST 2017

24.05.2017, 16:19, "NIkolai Marchenko" <enmarantispam at gmail.com>:
> I was talking about the solution that assumes making a QArrayList type and deprecating QList entirely,
> not the one that aliases QList to QVector which I, personally, don't like, since it will produce a lot of the code perception problems and incorrect perfomance assumptions.

So, do you propose to replace QList with QArrayList in existing APIs? That would be a serious pessimization for small types.

> Not to mention people will still widely use QList as it's "easier to type "(don't laugh) and "looks like a default container by simplicity of its name"
> (again, don't laugh, I am just outlining potential problems with new users)
> On Wed, May 24, 2017 at 4:12 PM, Konstantin Tokarev <annulen at yandex.ru> wrote:
>> 24.05.2017, 15:49, "NIkolai Marchenko" <enmarantispam at gmail.com>:
>>> A semi-sane idea that I think no one has suggested yet:
>>> What if, starting from Qt6, QList becomes a wrapper for QArrayList with a contructor from this type?
>>> After all making existing code slightly _slower_ because of the wrapping overhead is way less problematic than breaking it outright.
>>> It will nudge the users of QLists that need to be fast to switch but will leave users of "default no brainer container" happy as they likely wouldn't even notice.
>> If existing Qt APIs switch from QList to QVector in Qt 6, such change will make it hard to support both Qt 5 and Qt 6 in the same code base.
>>> On Tue, May 23, 2017 at 5:27 PM, Thiago Macieira <thiago.macieira at intel.com> wrote:
>>>> On Tuesday, 23 May 2017 04:56:52 PDT Olivier Goffart wrote:
>>>>> In my opinion for Qt6, we should make prepend, takeFirst amortized O(1) in
>>>>> QVector.
>>>> That is not very difficult once we move the begin pointer out of the d pointer
>>>> and into the main QVector class. We need to add an interface to QArrayData to
>>>> shrink and expand the buffer without relocating it. With that, we practically
>>>> hide the allocated capacity information from QVector too.
>>>> --
>>>> Thiago Macieira - thiago.macieira (AT) intel.com
>>>>   Software Architect - Intel Open Source Technology Center
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>>> ,
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>> --
>> Regards,
>> Konstantin


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