A Programming Question

[Nish Nishant]

Marc Clifton wrote:

void Foo()

Marc Clifton wrote:

return ret;

*ahem* Nish :-D

[Marc Clifton]

Drew Stainton wrote:

I start by assigning a default return value to a local variable and then use that variable as part of the conditional in whatever loops I'm using - nested or otherwise.

Ah, very nifty! 20 years of programming, and I never thought of that. In fact, I don't think I've even ever seen it in other people's code. :doh: Marc VS2005 Tips & Tricks -- contributions welcome!

[Daniel Turini]

Predictable destructors is one of the places where C++ shines. So, in properly coded C++, a single exit point is one more of a "style", or personal preference, since the method cleanup will always be done. On other languages, multiple exit points can lead corrupt data or leaks, and can introduce bugs. So, as a general rule, I try to avoid *LOTS* of exit points. A couple of exit points is acceptable in my rules. But this is not a strong rule: formally, languages that have exceptions ALWAYS have multiple exit points, because an exception potentially can occur at any point.

[Marc Clifton]

Nishant Sivakumar wrote:

*ahem*

You realize you're the first one to catch that. :-D Good call! I may harrass people about spelling errors, but those are nothing compared to a bad programming example error! Marc VS2005 Tips & Tricks -- contributions welcome!

[Jeremy Falcon]

I use a return variable that gets assigned a default value. This way I can make sure that I'm always returning a valid value. I do break loops when the time calls for it, mainly because I don't want my code to be inefficient. Although I tend to use to use the break statement sparingly, more so I will use continue. If I need to break the iteration completely I'll do so in the conditions if possible (unless I’m modifying someone else’s code – I don't make many changes as possible in that regard because you never know what impact it could have on the system). The main reason I do this is because for a long method it makes it easier to follow the flow of execution IMO. Jeremy Falcon

[Lost User]

Graham Bradshaw wrote:

surely you don't process the rest of the elements anyway?

Of course not! That's what I meant by 'I include the variable in the conditional for the loop' For a linear search, the variable would be set to 'found' and the loop would terminate in the conditional on the next iteration. Cheers, Drew.

[Jeremy Falcon]

:laugh: I passed right over that one. Jeremy Falcon

[Lost User]

I rarely ever see this done as well. It's not as efficient as using 'break' because the loop has to hit the conditional for the next iteration before it can end. I find it much easier to read and debug. I was big on state and flow diagrams many years ago and this made it much easier to relate the diagrams to the implementation. Cheers, Drew.

[Blake Miller]

Really :omg: Not even: Something* SearchForSomething(...) { Something* pSomethingTested; Something* pSomethingFound = NULL; while( !pSomethingFound ){ pSomethingTested = GetPointertoWhatever(); if( pSomethingTest matches my search criteria ){ pSomethingFound = pSomethingTested; } } return pSomethingFound; } It really IS that simple and straightforward :->

[Leslie Sanford]

Drew Stainton wrote:

I start by assigning a default return value to a local variable and then use that variable as part of the conditional in whatever loops I'm using - nested or otherwise.

I use this approach as well, except when you using foreach because, of course, there's no place to test the conditional as there is in a for or while loop. Of course, one could use an enumerator in a while loop instead:

bool found = false;
IEnumerator en = someCollection.GetEnumerator();

while(!found && en.MoveNext())
{
if(en.Current == soughtAfterValue)
{
// Take some action.
found = true;
}
}

return found;

However, I usually take this approach:

bool found = false;

foreach(SomeObject obj in someCollection)
{
if(obj == soughtAfterValue)
{
// Take some action.
found = true;
break;
}
}

return found;

I think either way is fine, but I think the second approach is a little clearer. So I don't think breaks within loops are automatically bad. I do like to avoid more than one return within a method, however. I break this rule from time to time if I think it will make the algorithm clearer, but I like having one return at the bottom of the method.

[Jamie Nordmeyer]

Nope. I'll exit when I damn well please. ;) Kyosa Jamie Nordmeyer - Taekwondo Yi (2nd) Dan Portland, Oregon, USA

[Lost User]

I do try and aim on having a single exit point for methods, but with C++ it isn't quite as important IMHO (thanks to destructors and smart pointers, etc.) - and it can lead to some very deep nesting, which might not necessarily be that readable. Most people I've spoken to in the office agree that it is preferable to have a single exit point, especially when maintaining other peoples code. As for loops - I use break often. Shrug.

---

The Rob Blog
Google Talk: robert.caldecott

[Colin Angus Mackay]

It depends. Sometimes having just one exit point makes it easier to read. Sometimes it doesn't. I just try and write code that is easy to read and maintain. So, I don't have a hard and fast rule.

---

My: Blog | Photos "Man who stand on hill with mouth open will wait long time for roast duck to drop in." -- Confucious

[Andy Brummer]

I tend to try to keep local variables to a minimum so that multiple exit points don't cause a problem. I find they make code cleaner and easier to read as long as you don't have to change a lot of state in order to exit. Having to do that just tells me that the method is trying to do too much and needs to be simplified. I rarely have methods with blocks nested more then 1 or 2 deep, and never have nested try catch blocks.

[Lost User]

Leslie Sanford wrote:

So I don't think breaks within loops are automatically bad

I totally agree - didn't mean to imply they were bad. I don't like using them but that's just my choice. You're right about foreach. To be honest I don't use it if the loop has early termination conditions. In those cases I use an enumerator. I really like knowing up front all of the conditions the loop is dependent on. Cheers, Drew.

[Steve Mayfield]

he omitted this line: #define void MyRet; :rolleyes: ;) Steve

[Jim Crafton]

You're Satan, aren't you? :) ¡El diablo está en mis pantalones! ¡Mire, mire! Real Mentats use only 100% pure, unfooled around with Sapho Juice(tm)! SELECT * FROM User WHERE Clue > 0 0 rows returned Save an Orange - Use the VCF!

[Leslie Sanford]

About breaking out of foreach...

Drew Stainton wrote:

To be honest I don't use it if the loop has early termination conditions. In those cases I use an enumerator. I really like knowing up front all of the conditions the loop is dependent on.

You know, this is a good point. I will consider it next time I'm thinking about using foreach in that way.

[malharone]

Was this a trick question?? How can you have return ret; in a function of type void??? :wtf: :wtf: But just in case if this was a typo ... Return immidiately ... - if in a simple "If" and single "Else" block. If (condition) return x; else return false; - or if in a simple switch statement If I'm implementing a complex logic in my method, then I have a single point of exit. But then again, there is no one right way. My decision making also depends on my mood :) . - Malhar

[leppie]

Personally I use goto's for difficult flow control, screw style! Just get it working the best it can be! [update] counted 6 goto's in the C# part of xacc :). Here's a nice example:

//some code before
foreach (MRUFile mru in recentfiles)
{
if (mru.filename == filename)
{
mru.Update();
goto DONE;
}
}
recentfiles.Add( new MRUFile(filename));

DONE:
//some code after

Now I can already hear the cursing, but any other form of flow control, you need 1 or more variables to carry some (unneeded, and extra) state, and make the whole thing much less readable. :-D [update] xacc.ide-0.1-rc4 released! Download and screenshots -- modified at 16:19 Monday 14th November, 2005