Re: [Boost-users] [Boost.Program_options] String options parser

Subject: Re: [Boost-users] [Boost.Program_options] String options parser
From: Michael Powell (mwpowellhtx_at_[hidden])
Date: 2017-06-13 22:23:44

On Tue, Jun 13, 2017 at 5:09 PM, Belcourt, Kenneth via Boost-users
<boost-users_at_[hidden]> wrote:
> Hi,
>
> We have an executable that uses the program_options library to process
> command line options like this:
>
> $ ./hilbert.x -h
>   -b [ --hilbert ] arg (=1)             enable hilbert matrix
>   -e [ --epsilon ] arg (=0.001)         roundoff epsilon
>   -h [ --help ]                         help message
>   -i [ --input-file ] arg               process input file
>   -r [ --rank ] arg                     rank of matrix to construct
>   -t [ --tolerance ] arg (=1e-13)       linear tolerance
>   -v [ --inverse ] arg (=0)             enable inverse hilbert matrix
>   -w [ --wordsize ] arg (=8)            floating-point word size (bytes)
>
> and it works great.  Now we’re trying to automate some testing and we test
> our executable with an input file that has hundreds of lines like this:
>
> --inverse 1 --tolerance 1e-15 --rank 2
> --inverse 1 --tolerance 1e-15 --rank 3
> --inverse 1 --tolerance 1e-15 --rank 4

When I've used BPO with input sources, I've used "INI" file format,
but I think it may also support other formats like Xml, Json, etc,
(?), but I could be wrong about that. Along the lines of this:

inverse=1
tolerance=1e-15
rank=2

If you have several different point of entry, that may work, I'm not
sure, or feed your subroutines several input sources, depending on how
you've implemented your input handlers:

inverse=1
tolerance=1e-15
rank=2
inverse=1
tolerance=1e-15
rank=3
inverse=1
tolerance=1e-15
rank=4

HTH

> where each line is a separate test case that we run with the specified
> options.  I was looking for a program options parser that can parse a
> string, so I can read one line of input from this file into a string, and
> run that test case, that is something like this:
>
>   // read one line of input from file
>   ifstream ifp;
>   string buffer;
>   while (!ifp.eof() && ifp.good()) {
>     getline(ifp, buffer);
>     // load a set of command line options from this string
>     po::parse_config_file<char>(buffer.c_str(), desc);
>   }
>
> The only program option parsers I see are parse_command_line,
> parse_config_file, and parse_environment.  Is there an easy way (without
> having to construct an argc/argv data structure) to parse a file of program
> options?
>
> — Noel Belcourt
>
>
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