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

A length restriction on a parameter list is just one more restriction. And restriction means applied violence. It sounds funny, but you can be non-violent even when programming. Just let the code dictate the rules. It is obvious that if you have many parameters, the body of the function/class method will be big enough to make use of them. And big code snippets usually can be refactored and split into smaller chunks. So you get solution against having many parameters as free bonus, since they are split among the smaller refactored pieces of code.

其他回答

我基本上同意5,但是,如果在我需要更多的情况下,这是解决问题的最清晰的方法,那么我会使用更多。

如果您开始在心里计算签名中的参数,并将它们与调用匹配,那么是时候重构了!

多了一个。我并不是说要油嘴滑舌,但是有些函数确实需要一些选项。例如:

void *
mmap(void *addr, size_t len, int prot, int flags, int fildes, off_t offset);

有6个论点,每一个都是必不可少的。此外,它们之间没有共同的联系来证明捆绑销售是合理的。也许你可以定义“struct mapargs”,但那更糟糕。

我同意3个是可以的,4个太多了。如果有3个以上的参数,你就不可避免地要做不止一个任务。一个以上的任务应该被分割成不同的方法。

然而,如果我查看我所从事的最新项目,例外情况比比皆是,大多数情况下很难归结为3个参数。

A length restriction on a parameter list is just one more restriction. And restriction means applied violence. It sounds funny, but you can be non-violent even when programming. Just let the code dictate the rules. It is obvious that if you have many parameters, the body of the function/class method will be big enough to make use of them. And big code snippets usually can be refactored and split into smaller chunks. So you get solution against having many parameters as free bonus, since they are split among the smaller refactored pieces of code.