Re: [Boost-users] Using program_options from a string?

Subject: Re: [Boost-users] Using program_options from a string?
From: Vladimir Prus (vladimir_at_[hidden])
Date: 2009-03-09 03:36:21

boostnewbie wrote:

> 
> Hello all.  I am using the boost::program_options library for configuration
> files with great success.  I'm wondering if it's possible to use the library
> using a string as a source, instead of a config file.
>  
> I read the configuration file with code like this:
>         if (vm.count("config")) {
>             string f = vm["config"].as<string>() ;
>             ifstream ifs(f.c_str());
>             store(parse_config_file(ifs, config_file_options), vm);
>             po::notify(vm);
>         }
> 
> but what I'd also like to do is something along these lines, with a string
> as the original source instead of a file specified with my 'config' command
> line option:
> 
>         string str = "port = 3000 \n tmpdir = /tmp \n";  // something like
> this. this is what's in the config file.
> istringstream iss(str, istringstream::in);
>         store(parse_config_file(iss, config_file_options), vm);
>         po::notify(vm);
> 
> These lines compile and execute without error but don't actually appear to
> update the 'vm'.  Am I doing something wrong or is this not possible with
> the current incarnation of program_options?

This should be possible. You might want to step into 'store' with a debugger
to check if:

  - parse_config_file actually returns nothing, or
  - store fails to do anything, or
  - the problem is elsewhere.

- Volodya