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Subject: Re: [std-proposals] std::error magic function
From: Tony V E (tvaneerd_at_[hidden])
Date: 2020-03-25 21:57:39


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.

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


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