[llvm-dev] [RFC] Error handling in LLVM libraries.

[Lang Hames via llvm-dev]

Hi Michael, Rafael, Pawel,

Apologies for the delayed reply - I was out on vacation last week.

>  In fact I would actually support outright
> replacing ErrorOr with this if it can be done safely, as I find the
> name TypedErrorOr a bit long.

I find the name awkward too. I'll leave these classes as TypedError and
TypedErrorOr<T> when I submit the initial patch to llvm-commits, but please
feel free to comment on the names in that review. If the proposal is
adopted I think the eventual plan should be to move to 'Error' and
'ErrorOr<T>', or Error and Expected<T> (Pawel - I really like that
suggestion - thanks!).

> The main differences are
> * This will hopefully be used.
> * TypedErrorOr is really a TypedError or T. The situation before was not
that ErrorOr was std::error_code or T.

I don't follow that second point. As I see it, TypedErrorOr<T> and
ErrorOr<T> are identical except for two points: TypedError replaces
std::error_code, and as a consequence TypedErrorOr is only movable, not
copyable.

Cheers,
Lang.

On Thu, Feb 18, 2016 at 7:40 AM, Paweł Bylica <llvm-dev at lists.llvm.org>
wrote:

> On Thu, Feb 18, 2016 at 4:36 PM Rafael Espíndola <llvm-dev at lists.llvm.org>
> wrote:
>
>> > I like this idea in general. It's a better implementation of what
>> > ErrorOr originally was before we removed the custom error support
>> > because it wasn't used. In fact I would actually support outright
>> > replacing ErrorOr with this if it can be done safely, as I find the
>> > name TypedErrorOr a bit long.
>>
>>
>> The main differences are
>> * This will hopefully be used.
>> * TypedErrorOr is really a TypedError or T. The situation before was
>> not that ErrorOr was std::error_code or T.
>>
>> Since we are adding it, I would also support replacing every use of
>> ErrorOr with TypedErrorOr and renaming it.
>>
>
> Alternative name could be Expected<T> as proposed by Andrei Alexandrescu.
>
>
>>
>> Cheers,
>> Rafael
>> _______________________________________________
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>> llvm-dev at lists.llvm.org
>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>
>
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