[boost] Re: program_options bool_switch usage string ... how to prettify?

From: Jonathan Graehl (jonathan_at_[hidden])
Date: 2004-09-14 16:21:29

Jonathan Graehl wrote:

> I used to do this:
>
>>>bool help_flag;
>>>options.add_options()
>>>        ("help,h","produce help message");
>>>help_flag=vm.count("help")
>>>
>>>      
>>>
>>  
>>
> Now this is better:
>
>>bool help_flag;
>>options.add_options()
>>        ("help,h", bool_switch(&help_flag),"produce help message");
>>
>>  
>>
>
> I tried it, and it works, but the usage string is a little odd:
>
>   -h [ --help ] arg (=0)    : produce help message
>   -v [ --version ] arg (=0) : print the version number

Apologies for self-reply:

It turns out that the "optional" nature of the argument to a bool_switch 
creates an impossible situation when positional arguments are used.  For 
instance:

myprogram -h positional_argument

will try to parse positional_argument as a bool if I use a bool_switch 
for the -h option

This seems like fairly useless behavior; bool_switch should *never* 
expect any argument (or, I should say, I'd like a version that doesn't 
consume my positional parameters).

Also, in parsers.cpp,

throw too_many_positional_options_error(
                            "too much positional options");

should be "too many positional options".

-Jonathan