Spiga

一天一个重构方法（17）：尽早返回

2009-07-02 19:23:29

Return ASAP：尽早返回

该话题实际上是诞生于移除箭头反模式重构之中。在移除箭头时，它被认为是重构产生的副作用。为了消除箭头，你需要尽快地return。

public class Order
{
	public Customer Customer { get; private set; }
	public decimal CalculateOrder(Customer customer, IEnumerable<Product> products, decimal discounts)
	{
		Customer = customer;
		decimal orderTotal = 0m;
		if (products.Count() > 0)
		{
			orderTotal = products.Sum(p => p.Price);
			if (discounts > 0)
			{
				orderTotal -= discounts;
			}
		}
		return orderTotal;
	}
}

该重构的理念就是，当你知道应该处理什么并且拥有全部需要的信息之后，立即退出所在方法，不再继续执行。

public class Order
{
	public Customer Customer { get; private set; }
	public decimal CalculateOrder(Customer customer, IEnumerable<Product> products, decimal discounts)
	{
		Customer = customer;
		decimal orderTotal = 0m;
		if (products.Count() == 0)
			return 0m;
		orderTotal = products.Sum(p => p.Price);
		if (discounts <= 0)
			return orderTotal;
		orderTotal -= discounts;
		return orderTotal;
	}
}