| Home | Libraries | People | FAQ | More

## Class options_description

boost::program_options::options_description

## Synopsis

    // In header: <boost/program_options/options_description.hpp>

    class options_description {
    public:
      // construct/copy/destruct
      options_description(unsigned = m_default_line_length,
                          unsigned = m_default_line_length/2);
      options_description(const std::string &, unsigned = m_default_line_length,
                          unsigned = m_default_line_length/2);

      // public member functions
      void add(shared_ptr< option_description >);
      options_description & add(const options_description &);
      options_description_easy_init add_options();
      const option_description &
      find(const std::string &, bool, bool = false, bool = false) const;
      const option_description *
      find_nothrow(const std::string &, bool, bool = false, bool = false) const;
      const std::vector< shared_ptr< option_description > > & options() const;
      void print(std::ostream &) const;

      // friend functions
      friend BOOST_PROGRAM_OPTIONS_DECL std::ostream &
      operator<<(std::ostream &, const options_description &);
      static const unsigned m_default_line_length;
    };

## Description

A set of option descriptions. This provides convenient interface for adding new option (the add_options) method, and facilities to search for options by name.

See here for option adding interface discussion.

option_description

### `options_description` public construct/copy/destruct

1.     options_description(unsigned line_length = m_default_line_length,
                           unsigned min_description_length = m_default_line_length/2);

   Creates the instance.

2.     options_description(const std::string & caption,
                           unsigned line_length = m_default_line_length,
                           unsigned min_description_length = m_default_line_length/2);

   Creates the instance. The 'caption' parameter gives the name of this 'options_description' instance. Primarily useful for output. The 'description_length' specifies the number of columns that should be reserved for the description text; if the option text encroaches into this, then the description will start on the next line.

### `options_description` public member functions

1.     void add(shared_ptr< option_description > desc);

   Adds new variable description. Throws duplicate_variable_error if either short or long name matches that of already present one.

2.     options_description & add(const options_description & desc);

   Adds a group of option description. This has the same effect as adding all option_descriptions in 'desc' individually, except that output operator will show a separate group. Returns *this.

3.     options_description_easy_init add_options();

   Returns an object of implementation-defined type suitable for adding options to options_description. The returned object will have overloaded operator() with parameter type matching 'option_description' constructors. Calling the operator will create new option_description instance and add it.

4.     const option_description &
       find(const std::string & name, bool approx, bool long_ignore_case = false,
            bool short_ignore_case = false) const;

5.     const option_description *
       find_nothrow(const std::string & name, bool approx,
                    bool long_ignore_case = false, bool short_ignore_case = false) const;

6.     const std::vector< shared_ptr< option_description > > & options() const;

7.     void print(std::ostream & os) const;

   Outputs 'desc' to the specified stream, calling 'f' to output each option_description element.

### `options_description` friend functions

1.     friend BOOST_PROGRAM_OPTIONS_DECL std::ostream &
       operator<<(std::ostream & os, const options_description & desc);

   Produces a human readable output of 'desc', listing options, their descriptions and allowed parameters. Other options_description instances previously passed to add will be output separately.