Re: [boost] Re: Re: [program_options] 1 suggestion + 1 question

From: Vladimir Prus (ghost_at_[hidden])
Date: 2004-05-07 10:06:29

Rob Stewart wrote:
> Vladimir Prus wrote:
> >    Usage: options_description [options]
> >    Allowed options:
> >      --help                    : produce help message
> >      --optimization arg (=10)  : optimization level
> >      -I [ --include-path ] arg : include path
> >      --input-file arg          : input file
> >
> > The (=10) is meant to give default value. The only problem I've found is
> > that we need to specify empty default value string for std::vector, which
> > leads to code like this:
> >
> >     ("second", value< vector<int > >()->default_value(vector<int>(1, 1),
> >     ""))
> >
> > Ok, maybe we just need 'vector_value' function which will take care of
> > default values.
>
> The default value could simply be given as a string in that case:
> "(1,1)" or whatever.  You could also use the OutputFormatters
> library when it is accepted into Boost.  (In that case, you just
> wait for your automated solution.)

In the highly likely case when the default value of vector is empty vector, 
output formatters will provide not very nice result.

I still think that ultimately we'd need 'vector_value', since

        ("second", vector_value<int>())

is a lot better than

        ("second", value< vector<int > >()->default_value(vector<int>(), ""))

- Volodya