Re: [Boost-users] program_options - ambiguous option

From: Vladimir Prus (ghost_at_[hidden])
Date: 2006-05-19 02:25:15

Santosh Joseph wrote:

> Code snippet is below...basically I have 2 options I
> want to process "host,s" & "help,h".
> I would like to process options like this:
> for host: --host, -host, -s
> for help: --help, -help, -h
> Maybe I setup the opt_style variable wrong or is this
> correct behavior?
> I'm using boost 1.33.1
> 
> when i run the program:
>> po.exe -host localhost -h
> *** Command line processing error: ambiguous option h

.....

      int opt_style =
     (po::command_line_style::unix_style |                    
      po::command_line_style::allow_long_disguise |
      po::command_line_style::allow_slash_for_short);

The important points here are that

1. 'unix_style' includes 'allow_guessing'
2. you explicitly specify allow_long_disguise

So, when program_options sees '-h' it first tries to parse it as 
long option, and due to 'allow_guessing' it checks for all long options
starting with 'h'. There are two such options, so you get an ambiguity.

If we first tried to parse every token as short option, then -help will be
parsed as option -h with value 'elp' -- probably not what you want.

I'd suggest that you mask out the allow_guessing style option.

- Volodya