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Subject: Re: [std-proposals] std::error magic function
From: Tony V E (tvaneerd_at_[hidden])
Date: 2020-03-25 21:58:33


On Wed, Mar 25, 2020 at 10:57 PM Tony V E <tvaneerd_at_[hidden]> wrote:

>
> Please include motivating examples.
>
> Preferably a table of examples, with C++20 code on the left that attempts
> to do something in the best C++20 possible way, and *better* code on the
> right that uses your feature.
>

And the code on the right is doing the same thing the code on the left is
trying to do.
(if that wasn't obvious)

>
>
> On Wed, Mar 25, 2020 at 9:44 PM connor horman via Std-Proposals <
> std-proposals_at_[hidden]> wrote:
>
>> I've done some work on this, and wrote a draft paper <
>> https://github.com/chorman0773/CXX-Papers/blob/master/std_error_function.md
>> >.
>> I am interested in any feedback.
>> I decided on a similar function, std::compiler_error, which has the same
>> compile time behavior, but its UB at runtime. This would allow users to
>> write std::error, with whatever runtime behavior they wish.
>> I would be interested in any feedback people have, both on the semantics,
>> and in the structure of the paper itself.
>> Thank you to the great people on the std-proposals mailing list.
>>
>> On Fri, 6 Mar 2020 at 11:07, connor horman <chorman64_at_[hidden]> wrote:
>>
>>> constinit won't downgrade (as the standard requires a constant
>>> expression initializer). I did forget about that.
>>>
>>> On Fri, 6 Mar 2020 at 10:13, Thiago Macieira via Std-Proposals <
>>> std-proposals_at_[hidden]> wrote:
>>>
>>>> On Friday, 6 March 2020 06:46:56 PST connor horman via Std-Proposals
>>>> wrote:
>>>> > Currently it is not possible to implement std::error in a way that it
>>>> will
>>>> > work with initializing non-constexpr variables. Throwing an exception
>>>> > simply downgrades to runtime, only erroring if the result is needed at
>>>> > compile time.
>>>>
>>>> Does that also apply to constinit variables?
>>>>
>>>> --
>>>> Thiago Macieira - thiago (AT) macieira.info - thiago (AT) kde.org
>>>> Software Architect - Intel System Software Products
>>>>
>>>>
>>>>
>>>> --
>>>> Std-Proposals mailing list
>>>> Std-Proposals_at_[hidden]
>>>> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>>>>
>>> --
>> Std-Proposals mailing list
>> Std-Proposals_at_[hidden]
>> https://lists.isocpp.org/mailman/listinfo.cgi/std-proposals
>>
>
>
> --
> Be seeing you,
> Tony
>

-- 
Be seeing you,
Tony


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