plz expain the code

Hello
           Can some one plz explain the below code particulary in bold

public class Cart { private readonly List<OrderItem> _items; private readonly IPricingCalculator _pricingCalculator;
// Poor man's IOC public Cart() : this(new PricingCalculator()) { }
public Cart(IPricingCalculator pricingCalculator) { _pricingCalculator = pricingCalculator; _items = new List<OrderItem>(); }
}