[program_options] Endless loop with long default arguments

[ensc]

when using a po::value with a representation of the default value
having a certain length, 'std::cout << opts' will stuck in an endless
loop.

E.g.

-----
#include <boost/program_options.hpp>
#include <string>
#include <iostream>

namespace po = boost::program_options;

int main(int argc, char *argv[])
{
  po::options_description		opts;
  opts.add_options()
    ("cfgfile,c",
     po::value<std::string>()->default_value("/usr/local/etc/myprogramXXXXXXXXX/configuration.conf"),
     "the configfile");

  std::cout << opts;
}
-----

| $ rpm -q boost
| boost-1.33.1-5
| 
| $ g++ foo.c  -lboost_program_options
| $ strace ./a.out
| ...
| write(1, "  -c [ --cfgfile ] arg (=/usr/lo"..., 80  -c [ --cfgfile ] arg (=/usr/local/etc/myprogramXXXXXXXXX/configuration.conf) 
| ) = 80
| write(1, "                                "..., 80                                                                               
| ) = 80
| write(1, "                                "..., 80                                                                               
| ) = 80
| ...



Removing one 'X' will result in an ugly

|   -c [ --cfgfile ] arg (=/usr/local/etc/myprogramXXXXXXXX/configuration.conf) t
|                                                                               h
|                                                                               e
|                                                                               c
|                                                                               o
|                                                                               n
|                                                                               f
|                                                                               i
|                                                                               g
|                                                                               f
|                                                                               i
|                                                                               l
|                                                                               e

output.


It would be nice, when:

- the default value could be moved into the description column
- the description would begin on a new line and an earlier column
  (e.g. 30-40) when option name/default-value are too long (> 30-40
  chars)

[nobody]

Logged In: NO 

Hit this one as well.

[s.ochsenknecht@…]

patch

[s.ochsenknecht@…]

I added a patch which solves this ticket.

When printing out all program options it will go to a new line and print out the description on the next line if the first part is too long. The output from the test case will look like the following with the patch:

  -c [ --cfgfile ] arg (=/usr/local/etc/myprogramXXXXXXXX/configuration.conf)
                                        the configfile
  -f [ --fritz ] arg (=/other/file)     the output file

Is it useful? Any comments?

I'm not a boost maintainer, so I'll better to keep the status of this ticket ... :-)

[Vladimir Prus]

(In [57271]) Put description to next line if we'd overflow otherwise. Fixes #689.

Patch from Sascha Ochsenknecht.

[Vladimir Prus]

Sascha, I have applied your patch. I have also added a testcase. Note that your patch had a few formatting changes, which I've left out in order not to mix semantic and formatting changes in one commit.

Thanks!