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Class template constrained_value

boost::CV::constrained_value — A template to specify a constrained basic value type.


// In header: <boost/date_time/constrained_value.hpp>

template<typename value_policies> 
class constrained_value {
  // types
  typedef value_policies::value_type value_type;

  // construct/copy/destruct
  constrained_value& operator=(value_type);

  // public member functions
  operator value_type() const;

  // public static functions
  static value_type max BOOST_PREVENT_MACRO_SUBSTITUTION() ;
  static value_type min BOOST_PREVENT_MACRO_SUBSTITUTION() ;

  // private member functions
  void assign(value_type) ;


This template provides a quick way to generate an integer type with a constrained range. The type provides for the ability to specify the min, max, and and error handling policy.

value policies A class that provides the range limits via the min and max functions as well as a function on_error that determines how errors are handled. A common strategy would be to assert or throw and exception. The on_error is passed both the current value and the new value that is in error.

constrained_value public construct/copy/destruct

  1. constrained_value(value_type value);
  2. constrained_value& operator=(value_type v);

constrained_value public member functions

  1. operator value_type() const;
    Coerce into the representation type.

constrained_value public static functions

  1. static value_type max BOOST_PREVENT_MACRO_SUBSTITUTION() ;
    Return the max allowed value (traits method).
  2. static value_type min BOOST_PREVENT_MACRO_SUBSTITUTION() ;
    Return the min allowed value (traits method).

constrained_value private member functions

  1. void assign(value_type value) ;