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Best and Worst Coding Standards?
An anonymous reader writes "If you've been hired by a serious software development house, chances are one of your early familiarization tasks was to read company guidelines on coding standards and practices. You've probably been given some basic guidelines, such as gotos being off limits except in specific circumstances, or that code should be indented with tabs rather than spaces, or vice versa. Perhaps you've had some more exotic or less intuitive practices as well; maybe continue or multiple return statements were off-limits. What standards have you found worked well in practice, increasing code readability and maintainability? Which only looked good on paper?"
Sound an awful lot like coding in C... no bad coding practice needed...
Seven Days with Ubuntu Unity
I've worked where we were supplied a full IDE and a 17" CRT, and the coding standard forced so much white space vertically that you had to basically remember all the code.
I've always found the Joint Strike Fighter's coding standards document an interesting read. It is available from Bjarne Stroustrup's website (pdf)
This sounds like a fairytale but I work for a very large IT firm which is very well known. Serious company doesn't mean good however.
In certain files (not all apparentely) all constant variables have to be declared globally. We are talking C++ here.
Think what you want, but I don't like it. The reason for the variables placements are so "that they will be easy to find".
First off, I'd suggest printing out a copy of the /. comments, and NOT read it. Burn them, it's a great symbolic gesture.
If Kernighan, Ritchie, and Torvalds does it like that, who am I to do differently.
Je ne parle pas francais.
My new standard comes from a 1950's comp sci book.
"Programs consists of input, output, processing and storage."
Lose focus of that and the project will be late, over budget and most likely broken in ways no one will understand for years.
I really don't get this obsession people have with putting braces on separate lines.
Block scoping is perfectly well indicated by indentation and blank lines are valuable for dividing functional blocks of code.
When you go and put all the braces on separate lines it totally kills the visual effect of the actually empty lines. Then you'll have to go and start using multiple blank lines for separating things and before long half the screen will be empty and mostly empty lines.
Hmmm perhaps that's it, maybe this is a scheme for people who don't like looking at the code.
It doesn't really matter what you do, so long as everyone on the team does the same thing.
If you are using your computer right, it does not only enable you to do things, it does the boring things for you, automatically.
Checkstyle is one of the tools in a company toolkit that is often overlooked but in fact VERY handy. It enables you to define a ruleset for your source code, finding stuff which is incompatible with the coding practice in your company/team/project/whatever. Moreover, you can stick it into Eclipse using the free Eclipse-CS plugin, so it will automagically mark the places which need to be change. Last but not least, you can put Checkstyle as an Ant task in your building environment (and in your continous integration toolkit) so commited code that does not conform certain standards does not build.
As for the rules themselves, we've found these to be the most successful:
Of course, we let developers to add suppresions for the 1% of false positives. In fact, there are very few suppresion rules set.
Build a tool even an idiot can use and only an idiot will want to use it. -S.O.B.
I don't like seeing opening braces sharing a line with anything else at all, unless the block gets closed on the same line.
if(something)
{
do_something();
}
else
{
do_something_else();
}
Yeah, it takes a bit more space, but I find it a lot easier to match blocks up when the braces are indented the same amount.
Without developer buy-in, whatever coding standards you come up with will be useless. IOW, ask your developers to create the standard together.
Je ne parle pas francais.
Make it "cut and paste" friendly, and as small as possible.
That's a really bad idea. Cut and paste causes code cloning, which is among the most difficult maintenance problems.
Code should be designed, when possible, in small chunks (methods, functions, etc.). This keeps the need to think about refactoring to a minimum, since the code is already factored. Well factored code has many other benefits, including easier-to-write unit tests and better understandability.
I maintain software that was originally written by someone as a prototype and eventually given production status. 4 years later, I am still pulling bugs out that relate to code cloning. Think of the guys who will maintain your software, please.
All my liberal friends think I'm a conservative, all my conservative friends think I'm a liberal.
The code is important. The braces are syntactical sugar.
I keep braces on their own line when coding c++, but I do my indentation differently:
if(something)
{
do_something();
}
else
{
do_something_else();
}
Well, as long as we're admitting that "readable" is an entirely subjective experience.. I'd have to say that I would find that notation less intuitive than the "} else {" construct.
It's too similar to consecutive 'if' statements which of course, breaks the logic.
Also, extending your notation logic fully results in:
if ( condition )
{
statement1;
}
else
{
statement2;
}
Which, although a waste of lines, is less confusing than your example.
That kind of code, when using PHP for templating, can make things much more efficient server side. Remember that anything within PHP tags is parsed by PHP. On a high volume site, even the relatively minuscule difference between passing something straight to the browser and echo("something"); can make a big difference in speed and resources.
:p
Besides, this is what syntax highlighters were made for. There are very good free ones on every single platform for a reason
ACs are modded -6. I don't read you, I don't mod you, I don't see you. Don't like it? Don't be a coward.
True - but at least it keeps thousands of otherwise dangerous PHP developers safely occupied.
There are other good reasons for putting open braces on their own line. The biggest is that most coding conventions have a maximum line width. If you have an 81-character line, you need to break it. When you are scanning down the code, all you see is a line at one indent level followed by another line indented more - you need to read the entire line to tell whether it's the start of a block or not. With braces on their own lines you can tell just by visual pattern matching where every block starts and finishes.
While I'm in holy-war territory, I'll also chime in on the tabs versus spaces argument. The tab character has a well-defined semantic meaning. It means 'indent this line / paragraph by one tabulator.' If you are indenting anything there is only one character you should be using - tab. It does not, however, have a fixed width, and should therefore never be used anywhere other than the start of a line or for aligning two lines. If you have to split a function across two lines, you should indent it like this:
Then, no matter whether the person reading your code thinks tabs should be 1 or 8 characters wide, arg1 and arg2 will always line up. Sadly, vim does not have the ability to distinguish marks used for indenting and marks used for alignment and so this has to be done manually.
I am TheRaven on Soylent News
the most egregious bug I think I ever introduced was due to code cloning. It was awful. I did not bother to properly refactor (hey it was 12 years ago) and as a result we ended up with diverging clones that needed to be separately maintained.
I worked for a company that was destroyed by a bad coding standard.
This was a small company, that, back in '96, was awarded the contract for a POS application for a regional store chain, with back-office servers that would be updated nightly by modem.
The guys who ran the company weren't programmers (though one of them knew enough to be dangerous); they were technical salesmen. They were also big fans of Microsoft, with "MVP" plaques on the walls, and every employee except me having Microsoft certs.
I worked for them part-time while also working for another company. I advocated Unix (mostly BSDI and SunOS at the time), and always argued with them about why Unix was better (technical superiority vs. potential for big profits).
When their big project was well underway, they brought me in to do the communications part of it, where the POS terminals would contact one of several servers by modem each night ("why not just ethernet them together, get a dialup PPP connection, and use IP? the interface is so much more reliable..." Request denied).
The app was Visual Basic, with third-party "custom controls" for things like talking to modems. My part went fairly smoothly, and I was eventually asked to help out with the main application, which was suffering from unexplained crashes. When I looked at the code, I found something... strange.
For error handling, they had elected to use a program called "VB Rig" (the name came from the rigging used on sailing ships, which prevents a sailor from falling to his death. Sometimes.) What this program did was to examine the source code, and then add error handling boilerplate at the start and end of each and every function. It inserted the exact same error handling code into every function.
Because the error handler had to be all purpose, it was about 20 lines of code per function - sometimes much larger than the regular part of the function. And, worse, because it was the same for every function, and it made use of the same variable names, that meant either every variable had to be global, or you'd have to declare the ten or so standard variable names at the start of every function (they opted for the "everything is global" approach).
Which led to things like this (forgive the syntax errors, it's been years since I've touched VB):
On Error goto my_data_file_read_function_VBRIG_TRAP
open MyDataFile for writing ...
goto my_data_file_read_function_VBRIG_CLEANUP
my_data_file_read_function_VBRIG_TRAP:
on error 101 'Permission Denied
delete MyDataFile
resume
on error 102 'File Not Found
MessageBox 'Cannot read ' + MyConfigFile
resume
my_data_file_read_function_VBRIG_CLEANUP:
blah blah
my_data_file_read_function = SUCCESS ' return
As you see, the error handling code - which had to be exactly the same for every function - made use of global variables (names like DataFile1, MyFile1, UserName, etc.) to figure out what to do for each error. That meant, that if there was any possibility you might have a "File Not Found", you had to expect the filename where that might happen to be in a particular global variable - say, MyFile1 - and hope that the calling function wasn't using that name too, for the same reasons.
Naturally, files were being created and deleted at random, and the programmers often spent hours on the phone with the customer trying to figure out why the Access database had disappeared *again*.
I asked if we could just write the error handling by hand, and use appropriate local variables; or take the standard VBRig error handling and trim out the lines that weren't relevant for a particular function (as subsequent VBRig runs wouldn't touch its code region if it saw that it had been customized).
Request Denied. "This is our coding standard. We carefully reviewed the options before making the decision to use t
.
Coding guidelines are typically justified because, as it goes, most of the time is spent fixing bugs in existing code than writing new code. The guidelines are needed because it helps others to come up to speed quickly while they try to figure out the code in which they have to fix the bug(s).
I think that is the wrong focus, as it tends to reinforce incorrect behavior, i.e., the writing of buggy code.
Coding guidelines should focus instead on the techniques that help reduce the number of bugs in code. How is that done? It takes someone (typically a senior person) looking at the the bugs that have been found in the code, categorizing their cause, devising a way to prevent those bugs from occurring, then putting that into the guidelines.
Keep the focus of the guidelines where it should be: to increase the quality of the software.
On the strange side is the omission of vowels on functions and varible names to save text space (it's not required, but should be consistent for similarily names objects). It sounds weird, but is still quite readable.
There are several tools that can detect cut and paste code:
Simian: http://www.redhillconsulting.com.au/products/simian/
PMD: http://pmd.sourceforge.net/
DuplicateFinder: http://www.codeplex.com/DuplicateFinder
And probably others
My Karma: ran over your Dogma
StrawberryFrog
Make it "cut and paste" friendly, and as small as possible.
Cut and paste causes code cloning, which is among the most difficult maintenance problems. Code should be designed, when possible, in small chunks (methods, functions, etc.).
Wait.. are you trying to say that copying the same lines of code over and over again must be avoided? So tell me genius, how else would you implement such a function without copying?
You just got troll'd!
Ding ding ding - we have a winner.
Real coders write code that you can take a ruler from any given close brace and draw a vertical line right up to the matching open brace, every time. Everybody else gets fired.
Lines are cheap. Time added trying to figure out an obfuscated code structure because somebody wanted to save lines (ie, put the open brace on the same line instead of doing the above) is expensive.
Glonoinha the MebiByte Slayer
That's the way I've always done it, but it seems like most published coding standards don't like it.
To reiterate: matching braces should line up horizontally AND vertically. It may "waste" lines, but the code is a lot more clear.
I also, except in some cases (like some class getter/setter methods, where they're just all one after each other and it's obvious what they are), use braces even if it's a single statement that's being executed within. I don't see why code should be inconsistent just because it's a single statement that's being executed.
I often get berated by other programmers for that style, but the only time I've applied for a job and had to stand at a white board and write code, and then describe my coding style, they seemed to appreciate it.
Stupid sexy Flanders.
Bollocks.
Draw your line from the closing brace up to the first line with any text on it, that line is the start of your block.
Having your opening braces on an empty line might be more aesthetically pleasing but has zero advantage in making the code clearer.
Either way, the most important thing is to have everyone do it the same way, every time.
I wish to remain anomalous
multiple return statements were off-limits
Despite the fact that it's not part of the coding standard where I work, I have a few coworkers who take this to the extreme. They surround every single function they write with: ... } while(0);
do{
And then, inside the "do" block, they just put "break" in any place where they would have otherwise put "return." It drives me insane; they insist that having a single exit point from your function makes it easier to debug, but I just don't get it. I've never even seen them use gdb, anyway, so I think that abusing "printf" is their idea of "debugging"...
One thing in our coding standard that I do like is that all variables that store units must have a unit specification at the end of their name -- in other words, all frequencies might have "Hz" or "MHz", distances might have "m" or "mm", times have "sec" or "msec", and so on. This is really helpful in my field -- it's not uncommon for me to open up a file that I've never looked at before and need to make modifications to it, and if the units everything things are stored in weren't immediately obvious, I'd have to go track down somebody and ask them. The annoying thing here is when people decide not to follow this standard because they think it should be obvious...
Karma: Terrifying (mostly affected by atrocities you've committed)
Duh, you so need to learn about this little thing called structured programming, which can totally help cut down on code duplication like that crap.
Here's a hint:
See? Much easier to understand than your spaghetti code, and much more maintainable too.
I've always found this to be clearer.
Drawing a line up to an opening brace doesn't tell you anything but the constraints of the code block, you then have to take another step to figure out what kind of code block it was.
If you draw the line up to the first text line then you'll not only know the constrains but you'll know immediately without any further inspection if it was a for block, a while block, a function, etc.
Punctanym: alternate spelling of words using punctuation or numerals in place of some or all of its letters; see 'leet'
That's what you're SUPPOSED to do. The real world would rather have absolutely nothing to do with any of that.
:)
In my short experience in the workin' world, I've come across some pretty spectacularly awful implementations of everything under the sun, from production boxes in shambles to network cables wrapped around sweaty water pipes to 2 year old production code passing GET strings straight to the SQL server unmodified (yay nonprofit sector!), and compromising code for a quick and dirty webpage so I can get things running just a bit faster is 1) the least of my worries and 2) a metric fuckton cheaper than new servers (yay nonprofit sector!).
ACs are modded -6. I don't read you, I don't mod you, I don't see you. Don't like it? Don't be a coward.
Messrs Kernighan and Ritchie and their no-necked associates would like to have a word with you out back.
Idiots who think like this write code that has to run every day, using the previous day's output as input, and takes 28 hours to run.
They think that you can have a baby in one month if you just put more men on the job.
You can't always "put more men on the job", and you want to write code that puts out web pages responsively. Some times algorithms are the key to page performance, and sometimes, it is just coding practice.
Try multiplying it by -1 and see if your stack is large enough.
Like many Python evangelists, you seem to have a remarkably limited experience of computer languages.
Here's a language with no braces:
Here's another:
Here's another:
Here's another:
or, more extensibly,
And the list goes on. Maybe you should try learning some other languages. Broaden your mind a bit. There's a lot out there that isn't Python or C/C++/Java. Some of it is quite interesting.
For one thing, they is grammatically plural.
--MarkusQ
Strangely enough, Hungarian worked quite well for the problem it was originally intended to solve.
I worked at Xerox in the late 70's and my manager was Charles Simonyi, inventor of this notation. The project was BravoX (grandparent of MS Word) and was written in BCPL. BCPL basically has one type: integer. How that integer is treated is purely a function of how you reference it. E.g. fooFirst>>fooNext means "use the variable 'fooFirst' as a pointer to a structure of type FOO, one of whose elements is (from the naming convention) a pointer to some other FOO." Whereas fooFirst+1 adds one to an integer and (almost certainly) yields an invalid point that bill blow up when you try to use it. (It's been 30 years since I wrote anything in it, so I probably screwed up the example.)
Since there was only one type, the compiler didn't/couldn't perform type checking. Hungarian was a way of putting the type into the name of the variable so that the programmer could perform visual type checking. There were 9 of us on the project and the consistency/readability across the code base was impressive. Any of us could go into anyone else's code and almost immediately see what was going on.
I still use a light variant of it in my own code, but when in someone else's code I try to stick to their naming/formatting convention.
Like so many good ideas, it worked well in its original context but became twisted out of shape when used for something never intended/envisioned by the original developers (even though the person doing the twisting was, in fact, the original developer!). Another example of this is the Third Eye Software symbol table format I created for my debugger, CDB, but which was then used and abused by Mips to create a complete piece of crap. What they did still has people swearing at me 20+ years after the fact. (More on this at Third Eye Software and the MIPS symbol table)
YOU FORTH LOVE IF HONK THEN