例程可以有参数,这不是新闻。您可以根据需要定义任意多的参数,但是过多的参数会使您的例程难以理解和维护。

当然,您可以使用结构化变量作为解决方法:将所有这些变量放在单个结构中并将其传递给例程。事实上,使用结构来简化参数列表是Steve McConnell在Code Complete中描述的技术之一。但正如他所说:

谨慎的程序员避免将数据捆绑在一起,除非逻辑上是必要的。

因此,如果你的例程有太多的参数,或者你使用一个结构体来掩盖一个大的参数列表,你可能做错了什么。也就是说,你没有保持耦合松散。

我的问题是,什么时候我可以认为一个参数列表太大?我认为5个以上的参数太多了。你怎么看?


当前回答

在最差的5个代码片段中,检查第二个,“这是一个构造函数吗”。它有37⋅4≈150个参数:

下面是一个程序员写的构造函数[…]你们中的一些人可能认为是的,它是一个很大的构造器,但他使用eclipse自动代码生成工具。NOO,在这个构造函数中,我发现了一个小错误,这让我得出结论,这个构造函数是手工编写的。(顺便说一下,这只是构造函数的顶部部分,它不是完整的)。

其他回答

这很大程度上取决于你工作的环境。以javascript为例。在javascript中,传递参数的最佳方式是使用带有键/值对的对象,这实际上意味着你只有一个参数。在其他系统中,最佳点将是3或4。

归根结底,这一切都取决于个人品味。

根据Perl最佳实践,3个是可以的,4个太多了。这只是一个指导方针,但在我们店里,这是我们努力遵守的。

我想说,只要你有2-4的过载,如果你需要的话,你就可以去更高的地方。

非常感谢你的所有回答:

It was a bit surprising to find people who also think (like I do) that 5 parameters is a good limit for the sanity of the code. Generally, people tend to agree that a limit between 3 and 4 is good rule of thumb. This is reasonable as people usually have a bad time counting more than 4 things. As Milan points, on average people can keep more or less 7 things in their head at a time. But I think that you can't forget that, when you are designing/maintaining/studying a routine, you have to keep in mind more things than just the parameters. Some people consider that a routine should have as many arguments as it needs to. I agree, but only for a few specific cases (calls to OS APIs, routines where optimization is important, etc). I suggest to hide the complexity of these routines by adding a layer of abstraction just above these calls whenever possible. Nick has some interesting thoughts on this. If you don't want to read his comments, I summarize for you: in a nutshell, it depends: I hate making hard and fast rules like this because the answer changes not only depending on the size and scope of your project, but I think it changes even down to the module level. Depending on what your method is doing, or what the class is supposed to represent, it's quite possible that 2 arguments is too many and is a symptom of too much coupling. The moral here is don't be afraid of showing your code to your peers, discuss with them and try to "identify areas where you have low cohesion and tight coupling". Finally, I think wnoise much agrees with Nick, and concludes his satirical contribution with this poetical vision (see comments below) of the art of programming: Programming is not engineering. Organization of code is an art because it depends on human factors, which depend too much on context for any hard rule.

短期记忆中的七件事?

函数名称 返回函数的值 函数的目的 参数1 参数2 参数3 参数4