Jim Lemon wrote:
Duncan Murdoch wrote:
On 8/31/2009 11:50 AM, Mark Knecht wrote:
On Mon, Aug 31, 2009 at 6:36 AM, Terry Therneau<thern...@mayo.edu>
wrote:
<SNIP>
The authors borrowed so much else from C, the semicolon would have been
good too.
Something I have thought myself.
I know real R coders will chuckle
I'd say cringe, rather than chuckle. This is going to make you waste
a lot of time some day, when you stare and stare at code like Terry's
and can't figure out what's wrong with it:
zed <- function(x,y,z) {
x + y
+z;
}
The value of the function is +z, not x+y+z, even though the C part of
your brain made you type it that way and reads it as one statement in
the body, not two.
This is getting interesting. One habit I have developed in R to
emphasize a line continuation is to always write the above as:
zed<-function(x,y,z) {
x+y+
z
}
That's a good habit. An alternative is to put parentheses around the
expression:
(x + y
+ z)
will work.
The trailing operator signalling to me and the interpreter that there's
more to come. A semicolon after the z would be innocuous. Now I know
that this marks me as a crabby old fart who learned to program on
Hollerith cards where there had to be firm conventions on when a line of
code ended. Still, given the moiety of global warming attributable to
endless discussions about how many spaces should be used for
indentation, I think the use of the semicolon as a personal aid to
interpretation is at worst a harmless affectation.
I think it's worse. To me, it's like putting in a comment that is
wrong, or writing code like this:
one <- 2
x <- x + one
Code has meaning, it's not just a bunch of binary instructions to the
computer. If the meaning and the look of the code clash, it is going to
lead to problems.
Duncan Murdoch
Jim
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