Relative Pointer auf Klassenmitglieder

Kann mir jemand eine Praktischen einsatz von "Relative Pointer auf Klassenmitglieder" schreiben, zeigen [...] ?

mfg Fragender

Gerard

#include <algorithm>
#include <functional>
#inlcude <iterator>
#include <iostream>
#include <string>
using namespace std;

#define for if(0);else for
const char newl = '\n'; 

struct Buch
{
    Buch(const string & titel_, const string & autor_, const string & isbn_)
     :titel(titel_), autor(autor_), isbn(isbn_)
    {}
    string titel;
    string autor;
    string isbn;
};

ostream & operator<< (ostream & os, const Buch & buch)
{
    const char newl = '\n'; 
    const char tab  = '\t';
    os << "<Buch>" << newl;
    os << tab << "<titel>" << buch.titel << "</titel>" << newl;
    os << tab << "<autor>" << buch.autor << "</autor>" << newl;
    os << tab << "<isbn>"  << buch.isbn  << "</isbn>"  << newl;
    os << "</Buch>" << newl;
    return os;
}

namespace PODTools
{
    template
    <
        typename TofStruct, 
        typename TofMember, 
        typename Predicate
    >
    class Member_t : public binary_function<TofStruct, TofStruct, bool>
    {
    public:
        typedef TofMember (TofStruct::*MemberPtr);

        Member_t(MemberPtr pMember, Predicate pred)
         :  m_pMember(pMember), 
            m_pred(pred)
        {
        }

        bool operator() (const TofStruct & lhs, const TofStruct & rhs) const
        {
            return m_pred( lhs.*m_pMember, rhs.*m_pMember );
        }

    private:
        MemberPtr   m_pMember;
        Predicate   m_pred;
    };

    template<typename TofStruct, typename TofMember, typename Predicate>
    Member_t<TofStruct, TofMember, Predicate> Member(TofMember (TofStruct::*pMember), Predicate pred)
    {
        return Member_t<TofStruct, TofMember, Predicate>( pMember, pred );
    }

}

int main()
{
    Buch Buecher[] = 
    { 
        Buch( "OOP für Dummies",            "Marcus Bäckmann",      "3826629841" ), 
        Buch( "Effektiv C++ programmieren", "Scott Meyers",         "3827313058" ), 
        Buch( "Die C++-Programmiersprache", "Bjarne Stroustrup",    "382731660X" ), 
        Buch( "Entwurfsmuster",             "GoF",                  "3827318629" ),
        Buch( "Algorithmen in C++ ",        "Robert Sedgewick",     "3893194622" ),
        Buch( "C++ Ent- Packt",             "Herbert Schildt",      "3826607317" ),
        Buch( "Exceptional C++",            "Herb Sutter",          "3827317118" ),
        Buch( "Modern C++ Design",          "A. Alexandrescu",      "0201704315" ),
        Buch( "Effective STL",              "Scott Meyers",         "0201749629" )
    };

    Buch * const BuecherBegin  = Buecher;
    Buch * const BuecherEnd    = Buecher + sizeof(Buecher) / sizeof(Buecher[0]);

    sort( BuecherBegin, BuecherEnd, PODTools::Member( &Buch::titel, less<string>() ) ); //heute sortiere ich mal nach titeln

    copy( BuecherBegin, BuecherEnd, ostream_iterator<Buch>( cout, "\n" ) );

    Buch * const f = find_if( BuecherBegin, BuecherEnd, bind1st( PODTools::Member( &Buch::autor, equal_to<string>() ), "Scott Meyers" ) );
    if(f != BuecherEnd)
        cout << *f << endl;
}

ahja der name Member und member_t sind unpassend

[ Dieser Beitrag wurde am 01.05.2003 um 14:52 Uhr von Dimah editiert. ]