Re: [Boost-users] Command Line Options Questions

Subject: Re: [Boost-users] Command Line Options Questions
From: Jon Lederman (jonlederman_at_[hidden])
Date: 2016-03-07 08:32:42

Hi,

I tried like this:

std::ostream& operator<<(std::ostream& os, const dsp_type& obj)
{
  // write obj to stream
  os << obj.value;
  return os;
}
std::istream& operator>>(std::istream& is, dsp_type& obj)
{
  // read obj from stream
  if ( 0 /* T could not be constructed */ )
    is.setstate(std::ios::failbit);
  is >> obj.value;
  return is;

}

However now it let’s everything through and doesn’t validate.  What is the proper way to do this?

-Jon
> On Mar 6, 2016, at 3:50 PM, Daniel Hofmann <daniel_at_[hidden]> wrote:
> 
> You have to implement operator<< otherwise the compiler does not know how to print (pipe it into an ostream) dsp_type.
> 
> You can use Boost.Fusion's I/O feature and BOOST_ADAPT_STRUCT like this
>> https://github.com/daniel-j-h/argparse-generic/blob/master/example.cc
> to make your life easier.
> 
> On March 6, 2016 5:43:27 PM GMT+01:00, Jon Lederman <jonlederman_at_[hidden]> wrote:
>> Hi,
>> 
>> I have two questions re: the boost command line options library:
>> 
>> 1) I am compiling a dynamic library that links to the boost command
>> line options library as a shared library.  When I try to unload the
>> dynamic library, I find that it isn’t properly unloaded and the boost
>> library seems to be causing the issue.  I did find that things were
>> helped somewhat when I linked to the boost static libraries.  However,
>> it still feels unstable.  Are there any particular things I should know
>> about in this context in terms of how my makefile should be linking to
>> boost?  Or are there other things I should look at.
>> 
>> 2)  When using program options, I am getting the following error.  For
>> some reason this seemed to work with the dynamic libraries (or it may
>> be a coincidence).  Am I required to implement the << and >> operators?
>> It had been compiling previously and stopped.  After googling this
>> issue there seems to be a lot of confusion.  Any help would be greatly
>> appreciated.
>> 
>> 
>> 
>> in file included from /usr/include/boost/any.hpp:27:0,
>>        from /usr/include/boost/program_options/value_semantic.hpp:12,
>>   from /usr/include/boost/program_options/options_description.hpp:13,
>>                from /usr/include/boost/program_options.hpp:15,
>> from
>> /usr/local/src/freeswitch/src/mod/applications/mod_sc_dsp/mod_sc_dsp.cpp:23:
>> /usr/include/boost/lexical_cast.hpp: In instantiation of 'struct
>> boost::detail::deduce_target_char_impl<boost::detail::deduce_character_type_later<dsp_type>
>>> ':
>> /usr/include/boost/lexical_cast.hpp:415:89:   required from 'struct
>> boost::detail::deduce_target_char<dsp_type>'
>> /usr/include/boost/lexical_cast.hpp:674:92:   required from 'struct
>> boost::detail::lexical_cast_stream_traits<std::basic_string<char>,
>> dsp_type>'
>> /usr/include/boost/lexical_cast.hpp:2363:19:   required from 'static
>> Target boost::detail::lexical_cast_do_cast<Target,
>> Source>::lexical_cast_impl(const Source&) [with Target = dsp_type;
>> Source = std::basic_string<char>]'
>> /usr/include/boost/lexical_cast.hpp:2543:50:   required from 'Target
>> boost::lexical_cast(const Source&) [with Target = dsp_type; Source =
>> std::basic_string<char>]'
>> /usr/include/boost/program_options/detail/value_semantic.hpp:89:38:  
>> required from 'void boost::program_options::validate(boost::any&, const
>> std::vector<std::basic_string<charT> >&, T*, long int) [with T =
>> dsp_type; charT = char]'
>> /usr/include/boost/program_options/detail/value_semantic.hpp:170:55:  
>> required from 'void boost::program_options::typed_value<T,
>> charT>::xparse(boost::any&, const std::vector<std::basic_string<charT>
>>> &) const [with T = dsp_type; charT = char]'
>> /usr/local/src/freeswitch/src/mod/applications/mod_sc_dsp/mod_sc_dsp.cpp:484:1:
>> required from here
>> /usr/include/boost/lexical_cast.hpp:388:13: error: static assertion
>> failed: Target type is neither std::istream`able nor std::wistream`able
>> BOOST_STATIC_ASSERT_MSG((result_t::value ||
>> boost::has_right_shift<std::basic_istream<wchar_t>, T >::value),
>> 
>> 
>> desc.add_options()
>> 	("help", "Generates help message")
>> 	("dsp_type", po::value<dsp_type>(&params.dsp_type)->required(), “")
>> 
>> where dsp_type is this:
>> 
>> struct dsp_type {
>> 	dsp_type() {}
>> 	dsp_type(std::string const& val):
>> 		value(val)
>> 	{ }
>> 
>> 	std::string value;
>> };
>> 
>> and I have a validator defined as this:
>> 
>> void validate(boost::any& v,
>>             std::vector<std::string> const& values,
>>             dsp_type* /* target_type */,
>>             int)
>> {
>> using namespace boost::program_options;
>> //namespace po = boost::program_options;
>> 
>> // Make sure no previous assignment to 'v' was made.
>> validators::check_first_occurrence(v);
>> 
>> // Extract the first string from 'values'. If there is more than
>> // one string, it's an error, and exception will be thrown.
>> std::string const& s = validators::get_single_string(values);
>> 
>> if (s == "ladspa" || s == "audioweaver" || s == "gstreamer" || s ==
>> "lv2")  {
>>   v = boost::any(dsp_type(s));
>> } else {
>>   throw validation_error(validation_error::invalid_option_value);
>> }
>> }
>> 
>> 
>> 
>> 
>> 
>> /usr/local/src/freeswitch/build/modmake.rules:214: recipe for target
>> 'mod_sc_dsp.lo' failed
>> make[1]: *** [mod_sc_dsp.lo] Error 1
>> 
>> ------------------------------------------------------------------------
>> 
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