Re: How to declare a virtual member (not a function) in a class

[Simen Kjærås via Digitalmars-d-learn]

On Tuesday, 18 February 2020 at 12:37:45 UTC, Adnan wrote:
I have a base class that has a couple of constant member 
variables. These variables are abstract, they will only get 
defined when the derived class gets constructed.

class Person {
    const string name;
    const int id;
}

class Male : Person {
    this(string name = "Unnamed Male") {
        static int nextID = 0;
        this.id = nextID++;
        this.name = name;
    }
}

The compiler restricts me from assigning those two functions. 
How can I get around this?

const members can only be set in the constructor of the type that 
defines them. To set them in a subclass, forward the values to 
the superclass' constructor:

class Person {
    const string name;
    const int id;
    protected this(string _name, int _id) {
        id = _id;
        name = _name;
    }
}

class Male : Person {
    this(string name = "Unnamed Male") {
        static int nextID = 0;
        super(name, nextID++);
    }
}

--
  Simen