Re: [Boost-users] [program_options] setting defaults

From: Liam Routt (caligari_at_[hidden])
Date: 2005-03-14 20:13:10

Liam Routt wrote:
> The result was a segmentation fault or illegal instruction during the 
> destruction of my opts class (a wrapper that has several 
> options_descriptions and a positional_options_description; there are 
> methods like the add_option() above that allow various options to be 
> set, in general they put the value_semantic argument last, but otherwise 
> pass arguments directly through).
...
> What am I missing here? It is possible I'm having trouble with all 
> occurences of po::value<>...

OK, I think I'm ready to partially answer my own question.

Here's what I have, in simple terms:

class Options
{
...
   public:
      add_option(const char *name, const char *desc,
                 const po::value_semantic *val=NULL)
      { if ( val != NULL )
        { configfile.add_options() (name, val, desc);
          environ.add_options() (name, val, desc); }
        else { ... add options without val ... } }
...
   private:
      po::options_description  configfile;
      po::options_description  environ;
};

When I call Options::add_option() and pass a value semantic like 
value<int>(), that fucntion is called *once* and the result is passed to 
the add_options for both options_description instances. When they go to 
clean up, the same value_semantic * is being dealt with by both 
instances, and that causes a problem.

My aim here is to provide a single point of definition for options that 
should be looked for in multiple locations. If at all possible I want to 
reduce an option definition to a single line, and preferably I want to 
hide the specific Boost program options stuff from the level above this 
(I am using #defines for the value<>() calls). Is there a way I can do 
this easily?

In order to delay the evaluation of value<int>() I suppose I could use a 
macro rather than a method, perhaps... Hmmm...

Take care,

Liam
--
Liam Routt                                          Ph: [phone]
Research Programmer                               caligari_at_[hidden]
Computer Science, Melbourne University              (or liam_at_[hidden])