CODEWITHSUNDEEP
c++classoop
xKaihatsu
xKaihatsu

Reputation: 124

Is it possible to use class objects as variables in class definition?

I want to do something like this.

#include <iostream>
using namespace std;

class Instance {

public:
    const string ClassName = "Instance";
    string Name = ClassName;
    bool Archivable = true;
    Instance Parent;
    
};

int main() {
    
    Instance obj1;
    Instance obj2;
    
    obj2.Parent = obj1; // set the parent instance to obj1
    obj2.Parent.Name = "NewName"; // change the parent’s (obj1) name   to “NewName”
    
    cout << obj1.Name; // I want “NewName” to be printed out.
    
}

The problem is that I get an error, and I don’t know how to store objects as references.

Upvotes: 0

Views: 72

Answers (1)

Alexandre Senges
Alexandre Senges

Reputation: 1599

You're not storing a reference but a value, so basically it is going to copy the value of obj1 into obj2.Parent. So when you change obj2.Parent's value you update the nested object which is not a reference to the true parent.

You have a few ways to manage ownership of nested elements which all depends on the context.

You could store a pointer:

Instance *Parent;

You could store a reference, which is almost the same thing, but quite uncommon in my experience:

Instance &Parent;

The easiest and best way would be to store a smart_pointer:

std::unique_ptr<Instance> Parent;

Edit, a working example:

#include <iostream>
using namespace std;

class Instance {

public:
    const string ClassName = "Instance";
    string Name = ClassName;
    bool Archivable = true;
    Instance *Parent;
    
};

int main() {
    
    Instance obj1;
    Instance obj2;
    
    obj2.Parent = &obj1; // set the parent instance to obj1
    obj2.Parent->Name = "NewName"; // change the parent’s (obj1) name   to “NewName”
    
    cout << obj1.Name << endl; // I want “NewName” to be printed out.       
}

Upvotes: 1

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