[Interest] QMap and thread-safe.

[Mandeep Sandhu]

On Wed, Jul 24, 2013 at 8:40 PM, Thiago Macieira
<thiago.macieira at intel.com>wrote:

> On quarta-feira, 24 de julho de 2013 12:59:31, Mandeep Sandhu wrote:
> > >
> http://channel9.msdn.com/posts/C-and-Beyond-2012-Herb-Sutter-You-dont-know
> > > -blank-and-blank
> > Thanks for sharing this link. It was very informative. (BTW, this applies
> > only to C++11)
>
> It does not apply to anything.
>

What I meant with "it applies to C++11", is that the C++11 standard library
now follows/respects the correct meaning of "const", i.e all std lib's
const functions are thread safe and in turn they expect "user" defined
const functions to be thread-safe as well.

Though as you mentioned, is not enforced by the language.

The only thing thats tying it up with C++11 is that the correct
"interpretation" of const is being followed in the new C++11 std lib, isn't
this what he meant in the talk? CMIIW.


>
> This is an idea by Herb Sutter and, to be honest, I agree with him that
> const
> *should* mean that.
>
> But it doesn't. The language does not enforce anything. There's no way to
> guarantee that the user code in a const function is actually thread-safe.
> It's
> very easy to break out of the safety:
>
>         const_cast
>         mutable
>

But having a mutable in a const function is (logiaclly) right. Rather thats
how, Herb explains, one would implement a thread-safe const function.

On the other hand doing a const_cast, in a const function, looked more of a
work-around to make the compiler happy.

-mandeep



>
> --
> Thiago Macieira - thiago.macieira (AT) intel.com
>   Software Architect - Intel Open Source Technology Center
>
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