c++ - How to implicitly convert Qt objects to QString? -

what's best way of making all of commented code below work in standard c++/qt way?

class { public:     a() { }     virtual ~a() { }     virtual qstring tostring() { return "a"; } };  class b: { public:     b() { }     ~b() { }     qstring tostring() { return "b"; } };  int main(int argc, char *argv[]) {     qcoreapplication a(argc, argv);      a_;     b b_;      // qdebug() << a_;  // can make work overloading << yes?     // qdebug() << b_;      // qstring x = a_;  // how make work?     // qstring y = b_;      qstring s = a_.tostring(); // i'm doing @ present     qdebug() << b_.tostring(); // i'm doing @ present      return a.exec(); } 

i have hierarchy of instances of own qt classes derive same base class. i'd turn them strings implicitly in standard way displayed in qt ui:

i can explicitly myself above own standard method tostring above, it's not implicit , i'd rather follow qt or c++ convention believe there 1 i'm not aware of.

the strings displayed in q*view controls believe means overloading operator << won't enough on it's own.

you add so-called conversion function:

struct foo {     operator int() { return 5; } };  foo f; int = f; // uses operator convert int 

so in case, replace virtual qstring tostring() virtual operator qstring().

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that said, implicit operators frowned-upon. not casts frowned upon, you're allowing cast happen implicitly. c++0x allows tack on explicit conversion functions make sure explicitly cast, don't know compilers support that.

i think you'd better off leaving have, , adding:

// assume qdebug() convertible std::ostream std::ostream& operator<<(std::ostream& stream, const a& val) {     stream << val.tostring(); // need make function const, of course      return stream; } 

and leaving rest explicit.