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Can a class add friend classes at runtime in C++?


Can a class add friend classes at runtime in C++?

By : Brad Culley
Date : November 21 2020, 07:01 PM
To fix the issue you can do
I'd like to make some classes become friends of other classes at runtime. Is there a way to do this?
code :


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friend class : inherited classes are not friend as well?

friend class : inherited classes are not friend as well?


By : Tom
Date : March 29 2020, 07:55 AM
Hope this helps See: Friend scope in C++
Voted exact duplicate.
code :
I looks like inherited classes of B are not friend of class A.
I this a limitation of C++ or my mistake ?
Given a class and its friend class, are the latter's inner classes automatically friends to the former class?

Given a class and its friend class, are the latter's inner classes automatically friends to the former class?


By : lf963
Date : March 29 2020, 07:55 AM
it fixes the issue I think there are two issues at play here. One is that the code smells bad, as you say, and the second is that it doesn't compile on your system. Regarding the smell, yes, excessive use of the friend keyword often indicates bad OO design. It is generally better to give an object what it needs to do its job rather than pull something out of it, which is essentially what friend lets you do.
Large numbers of inner classes, IMO, are not that bad, as they merely serve to keep classes within the scope of another. This helps keep the namespace less cluttered and allows you to use common names across different functional areas.
code :
class A
{
    friend class B;

    int x;
};

class B
{
    class Inner
    {
    public:
        void foo(A& a)
        {
            a.x++;
        }
    };

public:
    void bbb()
    {
        Inner i;
        A a;

        i.foo(a);
    }
};

int main()
{
    B b;

    b.bbb();
}
Accessing member functions of other classes into member function of `this` class using composition or friend classes

Accessing member functions of other classes into member function of `this` class using composition or friend classes


By : Prattap
Date : March 29 2020, 07:55 AM
it fixes the issue FibonacciDynamic dy(); is declaration of method FibonacciDynamic fibonacci::dy();
you should remove parentheses to make it data member declaration:
code :
...
FibonacciDynamic dy;
...
Class templates and friend Classes

Class templates and friend Classes


By : zugie
Date : March 29 2020, 07:55 AM
I hope this helps . If you lookup the syntax for template friends, you'll find the right way to do it:
code :
class A {
    template<typename T>
    friend class B; // every B<T> is a friend of A

    template<typename T>
    friend void f(T) {} // every f<T> is a friend of A
};
friend class BinaryTree<T>;
Can a friend class create objects from its friend classes in C++?

Can a friend class create objects from its friend classes in C++?


By : user1534529
Date : March 29 2020, 07:55 AM
wish of those help This looks like a circular include.
"Hash_class.h" includes "remove_duplicates.h" "remove_duplicates.h" includes "Hash_class.h"
code :
#include "remove_duplicates.h"
friend class remove_duplicates;
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