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Flags and/or gotos are both reasonable approaches in languages that don't have a try...finally construct and I've written code using both approaches in many different languages. Since the OP was obviously C# I assumed that is what we were talking about, and in C# the try..finally (or the "using" construct, when applicable) is definitely the cleanest approach to making sure your resource cleanup happens, even when you don't think exceptions enter into the picture, though in my experience most cases where resource cleanup happens, exceptions at the .NET framework level are almost always a possibility.
And no I wouldn't suggest try..finally for the original post because no resource cleanup is involved.
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Ok, lets forget language (old C) specific concerns: Assuming you have exceptions, yes, I agree that you can reasonably handle many cases of premature returns that way.
However, my take on exceptions is that code running as expected shouldn't throw one! Finding an element with specific properties in a container does not warrant throwing an exception, whether or not you need clean-up.
Look at the following code, ignoring language specific elements:
int find(Container c, double value, double tol)
{
int result = INVALID_ID; do_some_intialization();
for(size_t index = 0; index < c.size(); ++index)
{
if (element.distance(value) < tol)
{
result = element.ID();
}
}
do_some_clean_up();
return result;
}
There are various solutions to short-cut the loop once it finds a fitting element:
1. use some command that breaks out of the innermost loop (in C/C++ you can use break)
2. attach the check (result==INVALID_ID) to the loop header, so it quits once you assign a valid ID. (not sure how to do that with for_each in C#, but a standard for loop lets you add an arbitrary number of stop conditions easily)
3. Introduce a flag variable that indicates when you're done searching. As it would pretty much just store the current value of (result==INVALID_ID) in this case, you might as well go with solution 2 above
4. throwing an exception, catching it with try/finally to ensure proper cleaning up
In this example, my suggestion of introducing a flag variable turns out to be unneccesary, as the result variable itself can be used to pretty much the same effect. In my experience, this is often the case, so the effort to use these kind of checks instead of premature returns or gotos is often rather low.
Using an exception would certainly work, but it conflicts with my understanding of what an exception means. Also, if you do catch actual error cases with exceptions within that same code, you need to make sure to not catch the 'good-case-exceptions' as errors!
If you have no problem with that, the more power to you. But I prefer not to go that route.
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I think you've completely misunderstood what I said. I am in no way advocating introducing new exceptions as a way of prematurely ending a loop. What I am advocating is using language constructs (try...finally or using(...)) specifically designed help ensure safe cleanup regardless of how you exit the function/procedure. It's simply cleaner and easier to get it right than using other methods, especially when there is the possibility of exceptions, which it turns out is almost always when using resources that need to be explicitly cleaned up in languages that provide those constructs.
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Stefan_Lang wrote: premature returns are almost always a bad idea
Definitely a code smell.
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No, is not. This "one return only" style you talk about always produces uglier code, and is usually slower. This is clearly a personal style preference of yours and you are entitled to it, but if you think there is a general rule that recommends only one return then you should know you are wrong.
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throw an exception 
To alcohol! The cause of, and solution to, all of life's problems - Homer Simpson
----
Our heads are round so our thoughts can change direction - Francis Picabia
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the 2 loops are a good example, but for me is easier to track multiple exit points than it is to track changes on a variable.
there may be a hundred variables involved, the return value can get reset, millions of things can happen, but when there's a return statement, i know it's over. whatever i've at that point is the result, i can track individual cases one at a time.
for me it's really easier to track execution paths this way, is it different for you?
the ammount of different opnions when we talk about code is just funny 
opnions are the oposite of highlanders, there can never be only one.
I'm brazilian and english (well, human languages in general) aren't my best skill, so, sorry by my english. (if you want we can speak in C# or VB.Net =p)
"Given the chance I'd rather work smart than work hard." - PHS241
"'Sophisticated platform' typically means 'I have no idea how it works.'"
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Vague but true.
There are only 10 types of people in the world, those who understand binary and those who don't.
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Just because you can doesn't mean you should.
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OriginalGriff wrote: I think that's an unnecessary restriction - I prefer to do all my validation code / user notification en mass at the top of a method, and exit immediately.
Exactly. I share the same view - do validation and exit as soon as possible, to avoid crippling the logic down the road.
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I totally agree with you guys. But its also important what your boss thins. For example when i used the same technique validations with fast returns i got scold how this shouldn't be done this way because when someone reads the code he wont understand a thing ?! And also this isn't a good practice ?!
Microsoft ... the only place where VARIANT_TRUE != true
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It seems a lot of people follow to this "rule" without ever questioning why. My manager was also an advocate of the "single return improves readability" fallacy until I explained to him why this wouldn't be the case with examples. Plus when I completely rewrote a ugly mass of haired code in our system into actually maintainable code, he was convinced.
I think it needs some luck, and having open-minded management helps too.
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I do not see the value in always only having one return from a function. When reading the code, you still need to look through the function for every place retValue is set, so it is not easier to follow or understand. If there is some clean-up to be done, then it does make sense. But if not, why keep to this rule if it provides no benefit? In the validation example someone else posted in this thread, the early returns provide easier to read code, rather than a long block of if/then/else.
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Quote: the early returns provide easier to read code
Easier to read is a matter of opinion. Some people think C# is easier to read than VB.
There are only 10 types of people in the world, those who understand binary and those who don't.
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ryanb31 wrote: I prefer the second method.
You can't be serious!
/ravi
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Quote: You can't be serious!
I do like to joke around a lot, but yes, I can be serious at times.
There are only 10 types of people in the world, those who understand binary and those who don't.
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So if the array contained a million strings, the first of which was "ABC", you'd check every single string even though you already know you have a match? 
/ravi
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No. I would exit the loop.
There are only 10 types of people in the world, those who understand binary and those who don't.
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And that's what example #1 does, not #2.
/ravi
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Yes, but it returns out of the function, which is the actual debate. So, example 2, even though it has several issues, it does not exit the function, which is what I support.
However, what I would do is set the variable as in example #2 and then exit the loop.
There are only 10 types of people in the world, those who understand binary and those who don't.
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ryanb31 wrote: However, what I would do is set the variable as in example #2 and then exit the loop.
Ah, OK then.
/ravi
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On top of everything else, you're post isn't even appropriate for this forum!
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I'm a fan of early exit, so I'd go with the first one (assuming that's what this post is about).
It doesn't really matter much in smaller routines like the one above, but when you have longer ones it can be difficult to follow retValue around the function to find out where you are really setting the return value. The first method is shorter because you can run a case through in your head without having to write down variables.
I think the question boils down to Early Exit versus Single Exit. There's a lot of debate on the merits of both so I think your answers are going to be somewhat distributed between them. I've yet to hear a debate for single exit that I agree with over the merits of early exit...
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Quote: it can be difficult to follow retValue around the function to find out where you are really setting the return value.
That's funny. That's the same reason people usually argue for single exit, in that it is hard to figure out why some code isn't running because it turns out there was a return statement earlier that you hadn't noticed.
To each his own.
There are only 10 types of people in the world, those who understand binary and those who don't.
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