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Comment by unwind | Hacker News Reader

Google are very strict about things like code style guides, so things like having incorrect spacing, or ivars that aren’t in alphabetical order, or lines wider than 80 chars, will all get picked up.

Is the part of instance variables having to be sorted alphabetically really true? I did a quick search but only found the C++ style guide, which says nothing like that.

It sounds absurd, instance variables should (imo) be grouped logically, not sorted by their names which are not very relevant when it comes to which belong together.

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Did you read the part about how it helps dealloc? I can see how that would be nice, if you don't have too many instance variables then it wouldn't be a big deal.

No, I missed that part ... I guess it makes some kind of sense, but it seems weird to assume that all instance variables need deallocation.

If I have a buffer, and a length, I'd like to keep them together in the code since they both are part of the same thing. The length, however, is likely some integer type that won't need mentioning when destroying the instance.

But, if you are forced to name alphabetically you might start naming those related instance variables in a related way (which wouldn't necessarily be bad). For example in your case you might have: myFileBuffer and myFileBufferLength which would hopefully be next to each other, no?

It sounds absurd, instance variables should (imo) be grouped logically, not sorted by their names which are not very relevant when it comes to which belong together.

Not to mention packing, which if you are compiling with enough warnings turned on, can get annoying. I like to use http://google-styleguide.googlecode.com/svn/trunk/cpplint/cp... on my code, but many of the warnings are more style preferences than anything (like where braces go). Still, I agree with most of their style guidelines, and it's nice having checks for things like unnecessary includes, missing includes and missing idempotency preprocessor guards.

Edit: BTW, yes, I'm talking primarily about C++; haven't done enough ObjC to know about packing there, so YMMV. As for dealloc arguments, again, I don't know how it's done in ObjC, but in C++ I think it's irresponsible these days to not be using something like shared_ptr<> if you are dealing with heap, thereby eliding the need to even handle deallocs.

Alphabetizing, or any canonical ordering, can help minimize merge conflicts. We require it for Java imports and lists all over, so I'm not surprised to see it here.

In some projects I've worked on, we allow logical groupings, provided comments that describe what they are, but then require alphabetizing within the groups.

Can't say whether it's true, but the purported reason was stated in the article (same sorting used for declaration and for deallocation, to make reviewing for memory leaks easier).

That's correct: here's the passage in question from the Google Objective-C style guide:

> dealloc should process instance variables in the same order the @interface declares them, so it is easier for a reviewer to verify.

One engineers idea of 'logical order' may not be another's, so alphabetical order seems as good a sorting method as any. And since the article itself doesn't link to the style guide, here it is:

http://google-styleguide.googlecode.com/svn/trunk/objcguide....

Google keep it regularly updated, so it includes newer developments like ARC and the modern literal syntax.

The style guide (in that link at least) doesn't actually enforce or even mention alphabetical order for ivars. It seems an unusually proscriptive restriction for what's quite a reasonable style guide. The stated restriction - dealloc in declaration order - makes a lot of sense.

(Also, line lengths merely have to 'try' to be less than 80 characters, so there's wiggle room here too.)

Note that the public style guides aren't always a 1:1 match with the internal ones, usually for legacy reasons or to be more consistent with other internal languages.

I don't see anything offhand in the internal ObjC guide about alphabetical order for ivars, so it's possible the OP misunderstood the "dealloc in declaration order" rule. It's also possible his specific project had a convention of sorting them alphabetically.

Also different teams have slight variations from the official style guide.

'Logical' may indeed be an insufficient description given that it lacks any inherent substance (logic can demonstrate something which is true or false).

Personally I generally organize by kind: model (including state), and then interface (views, etc), and then controllers (including helpers).

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