Re: [boost] [program_options] implicit value and non-adjacent tokens

Subject: Re: [boost] [program_options] implicit value and non-adjacent tokens
From: Benedek Thaler (thalerbenedek_at_[hidden])
Date: 2016-12-21 02:40:57

Hi,

It is definitely how I see it.
Right after this change, which broke the tests of my program, I implemented
a value wrapper which mimics the original behavior.

I don't think there's is a single right way to do it, but consistency
matters.

Thanks,
Benedek

On Dec 21, 2016 08:37, "Vladimir Prus" <vladimir.prus_at_[hidden]> wrote:

>
> Hi,
>
> some time ago, program_options was modified so that options
> with implicit value would only take value from the same token.
>
> Previously, one could have:
>
>         ./program -a foo -b # uses 'foo' as value for 'a'
>         ./program -a -b     # uses some default value for 'a'
>         ./program -b        # has no value for 'a'
>
> Now, the first syntax interprets 'foo' as positional option,
> and one has two write
>
>         ./program -a=foo
>
> Ever since, I hear concerns from users about this behavior. Maybe not very
> loud, but quite consistent. Maybe, the new behavior is not
> very good, indeed, because it now mixes syntax matter (whether value
> is in the same token) with semantic matter (whether an option has
> implied value).
>
> I am considering reverting this change for next version of Boost.
> Does anybody have opinions either way?
>
> Thanks,
> Volodya
>
>
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