chargers

interface IChargable
{
    double LifeHours { get; }
}

class Battery : IChargable
{
    public double LifeHours { get { return 5.62; } }
}

abstract class Machine
{
    public abstract IChargable Charger { get; set; }

    public virtual int GetCurrentCharge()
    {
        //... логика за смятане на колко е зареден лаптопа до момента спрямо текущия чарджър, бил той батерия, зарядно..
        return 1;
    }
}

class Computer : Machine
{
    private IChargable charger;

    public Computer(IChargable charger)
    {
        this.charger = Charger;
    }

    public override IChargable Charger { get { return this.charger; } set { this.charger = value; } }
}

class Main
{
    static void Main()
    {
        IChargable battery = new Battery ();
        Machine comp = new Computer (battery);
        Console.WriteLine (comp.GetCurrentCharge ());
    }
}