繼承

class Animal
{
    abstract int maxSize(); // must be implemented by sub-class
    final float maxSizeInMeters() // can't be overridden by base class
    {
        return maxSize() / 100.0;
    }
}

class Lion: Animal
{
    override int maxSize() { return 350; }
}

void main()
{
    import std.stdio : writeln;
    auto l = new Lion();
    assert(l.maxSizeInMeters() == 3.5);

    writeln(l.maxSizeInMeters()); // 3.5
}