课堂设计问题 [英] class design question
问题描述
这是我前一段时间采访过的，我想知道
正确答案。设置是这样的;
如果我有一个基类食物还有两个类别肉。和veg
继承食物，因此;
食物
/ \
/ \
肉类蔬菜
我还有一个基类人类，所有人都吃，所以有一种方法
吃因此定义（*表示方法吃）
人类* ----无效（吃饭和食物）
/ \
/ \\ \\ b
素食食肉动物
现在的问题是我们如何处理这样的事情，以便vegaterian将b / b
从不吃肉，我们班级设计的条款等等。可能会有一两百万美元的答案但是我想从这个组的
专家那里得到最好的一个。
非常感谢周末愉快。
GrahamO
This came up in an interview I did a while ago and I wanted to know
the correct answer. The setup is this;
If I have a base class "food" and also two classes "meat" and "veg"
that inherit from food, thus;
food
/ \
/ \
meat veg
Also I have a base class human, and all humans eat so there''s a method
eat defined thus (* denotes the method eat)
human *----void (eat& food)
/ \
/ \
vegetarian carnivore
Now the question is how do we work things such that a vegaterian will
never eat meat, in terms of our class design etc. There''s probably a
million and one answers but I''d like to get the best one from the
experts on this group
thanks much and have a nice weekend.
GrahamO
推荐答案
* grahamo：
* grahamo:
如果我有一个基类食物还有两个类别肉。和veg
从食物中继承而来;
食物
/ \
/ \
肉类蔬菜
<另外我还有一个基类人类，所有人都吃，所以有一种方法因此定义吃（*表示方法吃）
人类* ----无效（吃饭和吃饭）
/ \
/ \\ /
素食食肉动物
现在的问题是我们如何处理这样的事情，一个vegaterian将
从不吃肉，就我们的班级设计等而言。可能有一百万个和一个答案，但我想从这个组的
专家那里得到最好的一个
If I have a base class "food" and also two classes "meat" and "veg"
that inherit from food, thus;
food
/ \
/ \
meat veg
Also I have a base class human, and all humans eat so there''s a method
eat defined thus (* denotes the method eat)
human *----void (eat& food)
/ \
/ \
vegetarian carnivore
Now the question is how do we work things such that a vegaterian will
never eat meat, in terms of our class design etc. There''s probably a
million and one answers but I''d like to get the best one from the
experts on this group
没有最佳答案。
如果你想让素食者吐出任何肉，我建议你检查了素食主义者对'吃'的动态食物类型。
如果你想要素食从不提供首先把肉作为食物，
我建议你删除一般的''吃'功能，或者让它不公开。
- -
答：因为它弄乱了人们通常阅读文字的顺序。
问：为什么这么糟糕？
答：热门发布。
问：usenet和电子邮件中最烦人的事情是什么？
There is no best answer.
If you want a vegetarian to spit out any meat it''s served, I suggest you check
the dynamic type of food in the vegetarian''s override of ''eat''.
If you want a vegetarian to never be offered meat as food in the first place,
I suggest you remove the general ''eat'' function, or make it non-public.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
这里给出的类层次结构违反Liskov替换
原则。原则规定：
在类层次结构中，应该可以处理专门的
对象
，就像它是一个基类对象。
以下文章详细描述了这一点：
http://www.eventhelix.com/RealtimeMa..._principle.htm
Deepa
-
EventStudio 2.5 - http：// www .EventHelix.com / EventStudio
以纯文本格式输入模型;以PDF / Word格式生成序列图
The class hierarchies presented here violates the Liskov Substitution
Principle. The principle states:
In class hierarchies, it should be possible to treat a specialized
object
as if it were a base class object.
The following article describes this in detail:
http://www.eventhelix.com/RealtimeMa..._principle.htm
Deepa
--
EventStudio 2.5 - http://www.EventHelix.com/EventStudio
Enter model in plain text;generate sequence diagram in PDF/Word
* EventHelix.com:
* EventHelix.com:
此处提供的类层次结构违反了Liskov Substitution
原则。
The class hierarchies presented here violates the Liskov Substitution
Principle.
其实没有。很多都没有具体说明。有一些更严格的
规格你会违反LSP，而其他则没有。
-
答：因为它弄乱了人们通常阅读文字的顺序。
问：为什么这么糟糕？
A：热门帖子。
问：usenet和电子邮件中最烦人的是什么？
Actually no. Much is left unspecified. With some sets of more rigorous
specifications you get LSP violations, with others not.
--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?
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