zypp::functor::functor_detail Namespace Reference

An unary functor forwarding to some other _Functor &. More...

Classes
struct	FunctorRef0
struct	FunctorRef1
struct	FunctorRef2
struct	nil

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Detailed Description

An unary functor forwarding to some other _Functor &.

Most algorithms take functor arguments by value. That's inconvenient if the functor wants to collect and return data. Creating and passing a FunctorRef to the algorithm, may help you out of this.

   // Counts invokations of operator().
   template<class _Tp>
     struct Counter : public std::unary_function<_Tp, void>
     {
       void operator()( _Tp )
       { ++_value; }

       Counter() : _value( 0 ) {}

       unsigned _value;
     };

   std::set<SomeType> c;
   Counter<SomeType> counter;
   // Invokations of FunctorRef are forwarded to counter:
   std::for_each( c.begin, c.end(),
                  // currently you must specify the
                  // operator() signature:
                  functorRef<void,SomeType>(counter)
                );

Note:

FunctorRef must be able to deduce the signature of _Functor::operator(). This is currently not automated, so you must specify the operator() signature as template arguments.

The order is <result_type, arg1_type, ...> (this differs from std::, where the result comes last).

Todo:

drop it an use boost::ref