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Class template overloaded_function

boost::overloaded_function — Function object to overload functions with distinct signatures.

Synopsis

// In header: <boost/functional/overloaded_function.hpp>

template<typename F1, typename F2, ... > 
class overloaded_function {
public:
  // construct/copy/destruct
  overloaded_function(const boost::function< F1 > &, 
                      const boost::function< F2 > &, ...);

  // public member functions
  boost::function_traits< F1 >::result_type 
  operator()(typename boost::function_traits< F1 >::arg1_type, 
             typename boost::function_traits< F1 >::arg2_type, ...) const;
  boost::function_traits< F2 >::result_type 
  operator()(typename boost::function_traits< F2 >::arg1_type, 
             typename boost::function_traits< F2 >::arg2_type, ...) const;
};

Description

This function object aggregates together calls to functions of all the specified function types F1, F2, etc which must have distinct function signatures from one another.

Parameters:

Fi Each function type must be specified using the following syntax (which is Boost.Function's preferred syntax):
    result_type (argument1_type, argumgnet2_type, ...)

In some cases, the make_overloaded_function function template can be useful to construct an overloaded function object without explicitly specifying the function types.

At least two distinct function types must be specified (because there is nothing to overload between one or zero functions). The maximum number of functions to overload is given by the BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX configuration macro. The maximum number of function parameters for each of the specified function types is given by the BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX configuration macro.

See: Tutorial section, make_overloaded_function, BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_OVERLOAD_MAX, BOOST_FUNCTIONAL_OVERLOADED_FUNCTION_CONFIG_ARITY_MAX, Boost.Function.

overloaded_function public construct/copy/destruct

  1. overloaded_function(const boost::function< F1 > &, 
                        const boost::function< F2 > &, ...);
    Construct the overloaded function object.

    Any function pointer, function reference, and monomorphic function object that can be converted to a boost::function function object can be specified as parameter.

    Note: Unfortunately, it is not possible to support polymorphic function objects (as explained here).

overloaded_function public member functions

  1. boost::function_traits< F1 >::result_type 
    operator()(typename boost::function_traits< F1 >::arg1_type, 
               typename boost::function_traits< F1 >::arg2_type, ...) const;
    Call operator matching the signature of the function type specified as 1st template parameter.

    This will in turn invoke the call operator of the 1st function passed to the constructor.

  2. boost::function_traits< F2 >::result_type 
    operator()(typename boost::function_traits< F2 >::arg1_type, 
               typename boost::function_traits< F2 >::arg2_type, ...) const;
    Call operator matching the signature of the function type specified as 2nd template parameter.

    This will in turn invoke the call operator of the 2nd function passed to the constructor.

    Note: Similar call operators are present for all specified function types F1, F2, etc (even if not exhaustively listed by this documentation).


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