Specific "getter setter" dedicated object

Question

I'd like to create an object used to store data, restricting read/write access.

For example :

OBJ obj1;
OBJ obj2;

// DataOBJ has 2 methods : read() and write()
DataOBJ dataOBJ1 (obj1);

With the code above, I want obj1 to access write() method, while other OBJ objects (obj2 in this case) should only access the read() method.

Is it possible to create a DataOBJ class restricting rights like that ?

The classical "getter setter" does not suit my needs.

Thanks.

Answer 1

You can control access to write/read by template global reference obj1/obj2 like in this example:

class OBJ {
};

OBJ obj1;
OBJ obj2;

// RESTRICTED ACCESS
class DataOBJBase {
protected:
   void write() {}
   void read() {}
};

template <OBJ&>
class DataOBJ;

// ALLOW WRITE IF FOR obj1
template <>
class DataOBJ<obj1> : public DataOBJBase {
public:
   using DataOBJBase::write;
};

// ALLOW READ IF FOR obj2
template <>
class DataOBJ<obj2> : public DataOBJBase {
public:
   using DataOBJBase::read;
};


int main() {
   DataOBJ<obj1> dobj1;
   dobj1.write(); // cannot read
   DataOBJ<obj2> dobj2;
   dobj2.read(); // cannot write
}