Subject: Re: [boost] [system] Would it be possible to trial a breaking change to Boost.System and see what happens?
From: Peter Dimov (lists_at_[hidden])
Date: 2018-01-12 19:03:25
Andrey Semashev wrote:
> void foo(error_code& err)
> {
> // Do stuff...
> err = make_error_code(success); // error_code(0, my_category)
> }
...
> I suppose, you could argue that I could avoid `err` initialization in
> `foo`, but that is a matter of taste and whether you want to rely on the
> initial state of `err` on entry into `foo`.
No, I'm not going to argue that; it's idiomatic to clear `err` on entry:
void foo( error_code& err )
{
err.clear();
// do stuff
}
with the alternative
err.assign( 0, err.category() );
being used nowadays to avoid the overhead in .clear caused by the "magic
static" Niall talks about.
This latter "idiom" is obviously broken after NIall's suggested change
though.
> I'm also not happy to have to convert that initialization to
>
> err = error_code();
>
> because it loses information about the error category, which may be useful
> if I want to print `err` to log even if it is a success.
Interesting. You rely on there being different success error_codes? This is
also in direct opposition to the requested change.
How would you suggest we solve the problem of zero being an error in some
contexts?