是否有充分的理由说明在函数中只有一个return语句是一个更好的实践?

或者在逻辑上正确的情况下,可以从函数中返回,这意味着函数中可能有许多返回语句?


当前回答

我想说的是,你应该有尽可能多的需要,或者任何使代码更干净的(如保护子句)。

我个人从来没有听过/见过任何“最佳实践”说你应该只有一个返回语句。

在大多数情况下,我倾向于根据逻辑路径尽快退出函数(保护子句就是一个很好的例子)。

其他回答

我曾经使用过糟糕的编码标准,强迫你使用单一的退出路径,如果函数不是琐碎的,结果几乎总是非结构化的意大利面条——你最终会遇到许多中断和继续。

Structured programming says you should only ever have one return statement per function. This is to limit the complexity. Many people such as Martin Fowler argue that it is simpler to write functions with multiple return statements. He presents this argument in the classic refactoring book he wrote. This works well if you follow his other advice and write small functions. I agree with this point of view and only strict structured programming purists adhere to single return statements per function.

I lean towards using guard clauses to return early and otherwise exit at the end of a method. The single entry and exit rule has historical significance and was particularly helpful when dealing with legacy code that ran to 10 A4 pages for a single C++ method with multiple returns (and many defects). More recently, accepted good practice is to keep methods small which makes multiple exits less of an impedance to understanding. In the following Kronoz example copied from above, the question is what occurs in //Rest of code...?:

void string fooBar(string s, int? i) {

  if(string.IsNullOrEmpty(s) || i == null) return null;

  var res = someFunction(s, i);

  foreach(var r in res) {
      if(!r.Passed) return null;
  }

  // Rest of code...

  return ret;
}

我意识到这个例子有点做作,但我很想把foreach循环重构成一个LINQ语句,然后将其视为一个保护子句。同样,在一个人为的例子中,代码的意图并不明显,someFunction()可能会有一些其他副作用,或者结果可能会在代码的// Rest中使用....

if (string.IsNullOrEmpty(s) || i == null) return null;
if (someFunction(s, i).Any(r => !r.Passed)) return null;

给出以下重构函数:

void string fooBar(string s, int? i) {

  if (string.IsNullOrEmpty(s) || i == null) return null;
  if (someFunction(s, i).Any(r => !r.Passed)) return null;

  // Rest of code...

  return ret;
}

在其他条件相同的情况下,单一出口点可以显著提高代码的可读性。 但有一个问题:流行的结构

resulttype res;
if if if...
return res;

是假的,“res=”不比“return”好多少。它只有一个return语句,但函数实际结束的地方有多个点。

如果你的函数有多个返回值(或“res=”s),最好将它分解成几个较小的函数,每个函数都有一个退出点。

你知道有句谚语——情人眼里出西施。

有些人信得过NetBeans,有些人信得过IntelliJ IDEA,有些人信得过Python,有些人信得过PHP。

在一些商店,如果你坚持这样做,你可能会丢掉工作:

public void hello()
{
   if (....)
   {
      ....
   }
}

这个问题完全是关于可见性和可维护性。

I am addicted to using boolean algebra to reduce and simplify logic and use of state machines. However, there were past colleagues who believed my employ of "mathematical techniques" in coding is unsuitable, because it would not be visible and maintainable. And that would be a bad practice. Sorry people, the techniques I employ is very visible and maintainable to me - because when I return to the code six months later, I would understand the code clearly rather seeing a mess of proverbial spaghetti.

嘿,伙计(就像一个前客户曾经说过的),做你想做的,只要你知道如何在我需要你解决它的时候解决它。

I remember 20 years ago, a colleague of mine was fired for employing what today would be called agile development strategy. He had a meticulous incremental plan. But his manager was yelling at him "You can't incrementally release features to users! You must stick with the waterfall." His response to the manager was that incremental development would be more precise to customer's needs. He believed in developing for the customers needs, but the manager believed in coding to "customer's requirement".

我们经常因为打破数据规范化、MVP和MVC边界而感到内疚。我们内联而不是构造函数。我们走捷径。

就我个人而言,我认为PHP是一种糟糕的实践,但我又知道什么呢?所有的理论争论都归结为试图满足一套规则

质量=精度,可维护性 和盈利能力。

所有其他规则都退居幕后。当然,这条规则永远不会消失:

懒惰是一种美德 程序员。