Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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Class value_semantic

boost::program_options::value_semantic

Synopsis

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


class value_semantic {
public:
  // construct/copy/destruct
  ~value_semantic();

  // public member functions
  std::string name() const;
  unsigned min_tokens() const;
  unsigned max_tokens() const;
  bool is_composing() const;
  bool is_required() const;
  void parse(boost::any &, const std::vector< std::string > &, bool) const;
  bool apply_default(boost::any &) const;
  void notify(const boost::any &) const;
};

Description

Class which specifies how the option's value is to be parsed and converted into C++ types.

value_semantic public construct/copy/destruct

  1. ~value_semantic();

value_semantic public member functions

  1. std::string name() const;

    Returns the name of the option. The name is only meaningful for automatic help message.

  2. unsigned min_tokens() const;

    The minimum number of tokens for this option that should be present on the command line.

  3. unsigned max_tokens() const;

    The maximum number of tokens for this option that should be present on the command line.

  4. bool is_composing() const;

    Returns true if values from different sources should be composed. Otherwise, value from the first source is used and values from other sources are discarded.

  5. bool is_required() const;

    Returns true if value must be given. Non-optional value

  6. void parse(boost::any & value_store, 
               const std::vector< std::string > & new_tokens, bool utf8) const;

    Parses a group of tokens that specify a value of option. Stores the result in 'value_store', using whatever representation is desired. May be be called several times if value of the same option is specified more than once.

  7. bool apply_default(boost::any & value_store) const;

    Called to assign default value to 'value_store'. Returns true if default value is assigned, and false if no default value exists.

  8. void notify(const boost::any & value_store) const;

    Called when final value of an option is determined.


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