[Development] QtCS 2017 QtCore sessions

[Konstantin Tokarev]

01.11.2017, 18:50, "Philippe" <philwave at gmail.com>:
>>  Using unsigned for size types is crucial in preventing signed overflow in
>>  pathological cases.
>
> During this interactive conference of "C++ gurus" (Herb Sutter, Bjarne
> Stroustrup, Andrei Alexandrescu, Stephan T. Lavavej, Chandler Carruth,
> Sean Parent, Scott Meyers, Michael Wong), it is clearly stated that it's
> generally a mistake to use unsigned...
> Check these extracts!
> https://www.youtube.com/watch?v=Puio5dly9N8#t=12m12s
> https://www.youtube.com/watch?v=Puio5dly9N8#t=42m40s
> https://www.youtube.com/watch?v=Puio5dly9N8#t=1h2m50s

I've listened and I think I buy this. Their main argument is about mixing unsigned and
signed, and Qt is a framework for a wide audience, and many people seem to
pass negative numbers to APIs accepting unsigned without second thought
(it's just a compiler warning, who looks at them after all), so using unsigned may
increase number of bugs on user side.

>
> Philippe
>
> On Wed, 01 Nov 2017 18:25:01 +0300
> Konstantin Tokarev <annulen at yandex.ru> wrote:
>
>>  01.11.2017, 18:21, "Thiago Macieira" <thiago.macieira at intel.com>:
>>  > On quarta-feira, 1 de novembro de 2017 05:23:04 PDT ???? ?????????? wrote:
>>  >>  Sorry for digging the thread, but how is
>>  >>  * use qssize_t
>>  >>  and
>>  >>  ** Wrapping std::{unordered_}map may be acceptable
>>  >>   combines?
>>  >>  std::*map uses size_t in it's API (size, max_size, count, reserve,
>>  >>  begin(size_type), end(size_type))
>>  >
>>  > Our wrapper API can still use qssize_t.
>>  >
>>  > "Won't that limit the actual maximum size?"
>>  >
>>  > No, not really, since it's already limited to half the full VM space. No
>>  > object can be larger than that. Using unsigned is unnecessary.
>>
>>  Using unsigned for size types is crucial in preventing signed overflow in
>>  pathological cases.
>>
>>  >
>>  >>  And offtop - what about allocators? They would be accesibble for wrappers,
>>  >>  but not accesible for QVector/QString?
>>  >
>>  > They wouldn't be accessible for wrappers either.
>>  >
>>  > --
>>  > Thiago Macieira - thiago.macieira (AT) intel.com
>>  >   Software Architect - Intel Open Source Technology Center
>>  >
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>>
>>  --
>>  Regards,
>>  Konstantin
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-- 
Regards,
Konstantin