public GSM(string model, string manufacturer, decimal? price, string owner,
Battery batteryInitial, Display displayInitial)
{
this.Model = model;
this.Manufacturer = manufacturer;
this.Price = price;
this.Owner = owner;
this.Battery = batteryInitial;
this.Display = displayInitial;
this.CallHistory = new List<Call>();
}
public GSM(string model, string manufacturer, decimal? price, string owner, Battery battery)
: this(model, manufacturer, price, owner, battery, new Display())
{
}