Stylistic questions on UNIX C coding.
in [Unix Programming]
|
Prev: integer
Next: shared memory question
From: Seebs on 5 Mar 2010 13:26 On 2010-03-05, Richard Heathfield <rjh(a)see.sig.invalid> wrote: > This is C we're discussing, not English. It is folly to pretend that the > rules of English apply to C. Actually, I'm not exactly talking about English. I'm talking about the underlying cognitive structures English (and every other language) maps to. So far as I know, regardless of language, humans distinguish between the topic and the comment (thanks to another poster for providing the terminology). > Ignoring. Probably a minor thinko on his part, no big deal. Not a big deal, but oddly, somewhat related -- it's the kind of mistake that shows up as a side-effect of added complexity. If you add enough parentheses to an expression, people will start mismatching them or putting them in the wrong places because they can't track them automatically anymore, or because the automatic tracking fails. For me, swapping the "natural" order of a comparison (I expect the "topic" to be first) is one extra layer, similar to an indirection, extra set of parentheses, or whatever. I don't know how common that is, but I'm pretty sure it's not going to change in the forseeable future. -s -- Copyright 2010, all wrongs reversed. Peter Seebach / usenet-nospam(a)seebs.net http://www.seebs.net/log/ <-- lawsuits, religion, and funny pictures http://en.wikipedia.org/wiki/Fair_Game_(Scientology) <-- get educated!
From: Keith Thompson on 5 Mar 2010 15:18 ImpalerCore <jadill33(a)gmail.com> writes: > On Mar 5, 12:13 pm, la...(a)ludens.elte.hu (Ersek, Laszlo) wrote: >> In article <4JydnbCdGNgatgzWnZ2dnUVZ7rydn...(a)bt.com>, >> >> Richard Heathfield <r...(a)see.sig.invalid> writes: >> > Ersek, Laszlo wrote: >> >> Because when read out loud, "i" is the subject. >> >> > Again, your comment would only be relevant if this were English, which >> > it isn't. >> >> Exactly -- I'm a staunch member of the "7 == x" camp. I just tried to >> explain why, as I perceive, Seebs thinks what he thinks. (Sorry if this >> qualifies as bad etiquette.) > > Are you a staunch member of the '7 == x' because of style, or because > of the possibility of catching '7 = x' errors? I personally don't > like the style simply because it *is* more mind taxing, and it's a > result of not seeing code in that style, not writing code in that > style, and not thinking about code in that style, for about 8 years > between C++ and C, that my brain has been conditioned that way. I > would be bold enough to say that a large majority of C programmers are > conditioned that way, simply from other people's code and books that > I've seen. [...] I have a question for those who like and/or use the '7 == x;' style. The usual rationale for the '7 == x' style is that it makes it easier to catch errors where you type "=" rather than "==". Would you even consider writing '7 == x' rather than 'x == 7' if C's equality and comparison operators were more distinct? For example, consider a hypothetical C-like language in which the equality operator is spelled "=" and the assignment operator is "<-", and "==" is a syntax error. (Yes, that would quietly break "x<-1"; let's ignore that.) In such a language, would you ever write "if (7 = x)" in preference to "if (x = 7)"? If so, why? -- Keith Thompson (The_Other_Keith) kst-u(a)mib.org <http://www.ghoti.net/~kst> Nokia "We must do something. This is something. Therefore, we must do this." -- Antony Jay and Jonathan Lynn, "Yes Minister"
From: Ian Collins on 5 Mar 2010 15:28 Keith Thompson wrote: > > I have a question for those who like and/or use the '7 == x;' style. > > The usual rationale for the '7 == x' style is that it makes it > easier to catch errors where you type "=" rather than "==". Good development practices (unit testing) will catch that typo. > Would you even consider writing '7 == x' rather than 'x == 7' > if C's equality and comparison operators were more distinct? > > For example, consider a hypothetical C-like language in which the > equality operator is spelled "=" and the assignment operator is > "<-", and "==" is a syntax error. (Yes, that would quietly break > "x<-1"; let's ignore that.) > > In such a language, would you ever write "if (7 = x)" in preference > to "if (x = 7)"? If so, why? While not a programming language, most unit test harnesses (at least all those I've used) express test assertions as ASSERT( expected, actual ) so after using them for a while, placing the invariant on the left doesn't look so bad. Despite many years exposure to this testing style, I still place the invariant on the right in conditionals.... -- Ian Collins
From: Andrew Poelstra on 5 Mar 2010 16:02 On 2010-03-05, Ersek, Laszlo <lacos(a)ludens.elte.hu> wrote: > > Ben Bacarisse <ben.usenet(a)bsb.me.uk> writes: > >> lacos(a)ludens.elte.hu (Ersek, Laszlo) writes: >> >>>> Seebs wrote: >>>>> >>>>> Why do we write "i < 10" rather than "10 >= i"? >>> >>> "10 == i" satisfies the second but not the first. >> >> Either way, it's not really at the heart of the question unless you >> think the switch *caused* the typo. > > Yes, I thought (and think) that that was not unpossible. If my memory > serves, both Keith and Seebs have pointed out that they need to reorder > reverse-ordered relational operators in their heads (sorry if I'm making > this up now) or that it causes extra mental load or something to that > effect. So the typo may be related to the reversing process. > (I hope I haven't munged up the attributions; they were formatted funnily and I was having a tough time reading them, so I shuffled some >'s around.) As Seebs points out in his reply to this article, (i > 10) == !(i <= 10), while (i > 10) == (10 < i), which is quite a different beast. Also, the idiomatic "count up to 10" loop is: for(i = 0; i < 10; ++i) while "count down to 10" is: for(i = 10; i >= 10; ++i) For these reasons I didn't see the typo, even after lacos said that there /was/ one, a fact that initially escaped me completely. Like Keith and Seebs, I need to mentally reorder these kind of expressions to understand them. I do that simply by reading the words backwards, since reading and writing backwards is much easier for me than re-ordering and then "reading" different text from what I see. So I find it interesting that I made the same mistake. -- Andrew Poelstra http://www.wpsoftware.net/andrew
From: Rick Jones on 5 Mar 2010 16:10
In comp.unix.programmer Ike Naar <ike(a)localhost.claranet.nl> wrote: > It doesn't matter, but anybody can fool themselves that it does. > And then Alice convinces herself that 3+x is ugly and unreadable, > Bob opts for x+3 being error-prone and unreadable, and now what > should Carol write? The ISO, or perhaps her elected representative - there aught to be a law right?-) rick jones -- oxymoron n, Hummer H2 with California Save Our Coasts and Oceans plates these opinions are mine, all mine; HP might not want them anyway... :) feel free to post, OR email to rick.jones2 in hp.com but NOT BOTH... |