http://drdobbs.com/blogs/cpp/231902461

Anyone want to do the reddit honors?

Walter:

> http://drdobbs.com/blogs/cpp/231902461

It's a nice explanation, quite simple to understand, despite it lacks some details.

Bye,
bearophile

On Mon, 07 Nov 2011 20:08:27 -0500, Walter Bright <newshound2@digitalmars.com> wrote:

> http://drdobbs.com/blogs/cpp/231902461
>
> Anyone want to do the reddit honors?

http://www.reddit.com/r/programming/comments/m497s/type_qualifiers_and_wild_cards_in_the_d/

-Steve

On 11/08/2011 02:08 AM, Walter Bright wrote:
> http://drdobbs.com/blogs/cpp/231902461
>
> Anyone want to do the reddit honors?

Nice article!


> It isn't a template, and inout can only be used on function parameters and the return value.

What about local variables?

On 11/8/2011 12:16 AM, Timon Gehr wrote:
> Nice article!

Thanks!


>  > It isn't a template, and inout can only be used on function parameters and
> the return value.
>
> What about local variables?

Just use const for them.

On 08.11.2011 09:33, Walter Bright wrote:
> On 11/8/2011 12:16 AM, Timon Gehr wrote:
>> Nice article!
>
> Thanks!
>
>
>> > It isn't a template, and inout can only be used on function
>> parameters and
>> the return value.
>>
>> What about local variables?
>
> Just use const for them.

This compiles:

inout(int *) foo(inout(int *) a)
{
   inout x = a;
   return x;
}

and it doesn't compile if you replace 'inout x' with 'const x'.

On 11/8/2011 12:44 AM, Don wrote:
> This compiles:
>
> inout(int *) foo(inout(int *) a)
> {
> inout x = a;
> return x;
> }
>
> and it doesn't compile if you replace 'inout x' with 'const x'.
>

inout can implicitly convert to const, but const cannot implicitly convert to inout, hence the error on the return x;

But you're right, use inout in the body, and it is treated much like const.

Le 08/11/2011 02:08, Walter Bright a écrit :
> http://drdobbs.com/blogs/cpp/231902461
>
> Anyone want to do the reddit honors?

Great article. The only point I would raise is the choice of inout as a keyword for this.

This make no sens whatsoever. Here is why :
- inout did exist in D1 and is different.
- in and out qualifier already exists and have nothing to do with inout.
- in and out are used for contracts and have nothing to do with inout.
- the inout term has nothing to do with const/immutable/mutable. This is in a totally different lexical field.

Another keyword should be choosen. vconst, as suggested here : http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP2 is way more appropriate.

On external details, but still important, I face the need of inout few days ago and did knew about it. The documentation on const/immutable ( http://www.d-programming-language.org/const3.html ) doesn't mention it. The page on fucntion mention it, but it would be nice to have at least a link on the const/immutable page.

I agree with _inout_ being a bad choice.
I'd rather use something involving _auto_, because this kind of use of
_auto_ is already employed in _auto ref_ parameters and is visually
unambiguous.
Probably _auto const_ would do the trick.

The actual _inout_ keyword could be flagged as deprecated and removed during the next breaking change in D (along with all other wonderful breaking changes that were proposed).

On Tue, Nov 8, 2011 at 5:08 PM, deadalnix <deadalnix@gmail.com> wrote:
> Le 08/11/2011 02:08, Walter Bright a écrit :
>>
>> http://drdobbs.com/blogs/cpp/231902461
>>
>> Anyone want to do the reddit honors?
>
> Great article. The only point I would raise is the choice of inout as a keyword for this.
>
> This make no sens whatsoever. Here is why :
> - inout did exist in D1 and is different.
> - in and out qualifier already exists and have nothing to do with inout.
> - in and out are used for contracts and have nothing to do with inout.
> - the inout term has nothing to do with const/immutable/mutable. This is in
> a totally different lexical field.
>
> Another keyword should be choosen. vconst, as suggested here : http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP2 is way more appropriate.
>
> On external details, but still important, I face the need of inout few days ago and did knew about it. The documentation on const/immutable ( http://www.d-programming-language.org/const3.html ) doesn't mention it. The page on fucntion mention it, but it would be nice to have at least a link on the const/immutable page.
>

Le 08/11/2011 14:36, Gor Gyolchanyan a écrit :
> I agree with _inout_ being a bad choice.
> I'd rather use something involving _auto_, because this kind of use of
> _auto_ is already employed in _auto ref_ parameters and is visually
> unambiguous.
> Probably _auto const_ would do the trick.
>
> The actual _inout_ keyword could be flagged as deprecated and removed
> during the next breaking change in D (along with all other wonderful
> breaking changes that were proposed).
>

Well use of auto can be ambiguous here I think.

What about auto const ref ?