small syntax suggestion
hi ted, philippe, and others---I agree with everything you write about good coding practice. none of us would be writing x<-3, even when we want to assign 3. we know better. we would at least use a space, if not a paren. alas, my suggestion is not so much for you. It is trying to spare novices that are just beginning to use R some unnecessary frustration. I bet that most of us have made this mistake at least once. to the extent that it requires a token "<-[0-9]" to recognize this, it could be an easy special case/warning/error. to the extent that it requires more, it is probably not worth the hassle. [I am a great fan of syntax checking. I am not a great fan of many but the simplest recycling rules (from 1 to N) BY DEFAULT. It's just asking for trouble.] regards, /iaw ---- Ivo Welch (ivo.welch at brown.edu, ivo.welch at gmail.com) On Mon, Aug 23, 2010 at 4:27 PM, Philippe Grosjean
<phgrosjean at sciviews.org> wrote:
I tell to my students that it is very important (not only for legibility) to place spaces between operands. They have to write such a code like this: if (x < -3) do_something That way, there is no ambiguity. Don't you think it's important to write clear code, including by using spaces where it makes it easier to read,... and less ambiguous, as you just realize? Best, Philippe Grosjean On 23/08/10 19:06, Davor Cubranic wrote:
On 2010-08-23, at 6:15 AM, Barry Rowlingson wrote:
On Sun, Aug 22, 2010 at 4:33 PM, ivo welch<ivo.welch at gmail.com> ?wrote:
I have found that my students often make the mistake of mixing up comparisons and assignments with negative numbers: ?if (x<-3) do_something;
If you tell your students not to use '<-' for assignment, then they can't make this mistake, because = for assignment has additional restrictions on it:
The students are trying to *compare* to a negative number, and trip on R's parsing of "<-". They could use '=' for assignment all they want (which I thought is being discouraged as a code style these days, BTW), and they'll still run into this problem. Davor
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