Should a function have only one return statement?
Are there good reasons why it's a better practice to have only one return statement in a function?
Or is it okay to return from a function as soon as it is logically correct to do so, meaning there may be many return statements in the function?
I often have several statements at the start of a method to return for "easy" situations. For example, this:
public void DoStuff(Foo foo)
{
if (foo != null)
{
...
}
}
... can be made more readable (IMHO) like this:
public void DoStuff(Foo foo)
{
if (foo == null) return;
...
}
So yes, I think it's fine to have multiple "exit points" from a function/method.
Nobody has mentioned or quoted Code Complete so I'll do it.
17.1 return
Minimize the number of returns in each routine . It's harder to understand a routine if, reading it at the bottom, you're unaware of the possibility that it returned somewhere above.
Use a return when it enhances readability . In certain routines, once you know the answer, you want to return it to the calling routine immediately. If the routine is defined in such a way that it doesn't require any cleanup, not returning immediately means that you have to write more code.
I would say it would be incredibly unwise to decide arbitrarily against multiple exit points as I have found the technique to be useful in practice over and over again, in fact I have often refactored existing code to multiple exit points for clarity. We can compare the two approaches thus:-
string fooBar(string s, int? i) {
string ret = "";
if(!string.IsNullOrEmpty(s) && i != null) {
var res = someFunction(s, i);
bool passed = true;
foreach(var r in res) {
if(!r.Passed) {
passed = false;
break;
}
}
if(passed) {
// Rest of code...
}
}
return ret;
}
Compare this to the code where multiple exit points are permitted:-
string fooBar(string s, int? i) {
var ret = "";
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;
}
I think the latter is considerably clearer. As far as I can tell the criticism of multiple exit points is a rather archaic point of view these days.
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