Re: protected constructor, std::list and friends

From:
 =?iso-8859-1?q?Elias_Salom=E3o_Helou_Neto?= <eshneto@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Tue, 06 Nov 2007 16:54:57 -0800
Message-ID:
<1194396897.576562.188060@o38g2000hse.googlegroups.com>
On 6 nov, 11:28, "Thomas Grund" <thomas.gr...@mail.com> wrote:

Hi,

In the following code I would like that the class Node is only be used by
the class Database. So the idea was to make the interface protected and
use the friend definition. The code does not compile because the list
needs an public destructor. Making list<Node> a friend of Node doesn't
help.


It does if done the right way. Try friend std::list< Node >. The
following should compile:

#include <list>

using namespace std;

class Node
{
        public:
        protected:
                void addChild()
                {
                        Children.push_back(Node());
                }

        private:
                list<Node> Children;

        friend class Database;
    friend class std::list< Node >;

};

class Database
{
        public:
                void addItem()
                {
                        n.addChild();
                }
                Node n;

};

int main()
{
        Database d;
}

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