On 05/01/2013 07:20 PM, Duncan Murdoch wrote:
On 13-05-01 4:08 PM, Tim Triche, Jr. wrote:
What harm comes of having the code be cut-and-paste-able?
I do not mean to be contrary but a downside to applying the patch
seems to
be lacking.
Perhaps I am missing something obvious and if so I beg your pardon for
wasting your time.
I think you are missing some downsides which may not be obvious:
- it would mean that lots of published results would no longer match
what R produces.
What kind of published results? Results that do statistics on the nb
of lines of code in a function based on the output of print.function()?
Would it make sense to try to reproduce results that were published 5
or 10 years ago with R >= 3.0.0? Too many things have changed in R
and on CRAN anyway so it's hopeless. The only reasonable/realistic way
to reproduce is to use the version of R and packages that were used
at the time of the publication.
- it would mean that lots of tests for changes in output would
suddenly fail.
Lots of tests really? Where are they?
- it would support the mistaken belief that some people have that the
current output is not valid code (even though there are nearly 200,000
instances of similar usage on CRAN).
Is that number supposed to impress someone?
Running
grep -E '^[[:space:]]*else' */R/*
produces 112,518 lines of output on the 4479 source packages currently
available on CRAN. So 112,518 "if else" statements use the formatting
that breaks copy/paste.
Also, interestingly, running
grep else */R/*
on those packages produces 276028 lines of output. So only 34% of the
"if else" statements use the formatting that breaks copy/paste. Far
from being the dominant idiom, which is probably a good sign for CRAN.
Unfortunately, with the current output of print.function(), 100% of
the "if else" statements on CRAN break copy/paste. Unfair for the
majority of CRAN contributors to see their nicely formatted code
exposed that way to the end-user. Unfair for the end-user, especially
the R novice, to get code s/he cannot copy/paste.
Perhaps 20 years ago it should have been written the way you suggest,
but it would cause far more harm than benefit to change it now.
You clearly underestimate the harm the current formatting causes
every day to many R users, developers, teachers, students...
H.
Duncan Murdoch
Thanks,
--t
On Wed, May 1, 2013 at 12:19 PM, Duncan Murdoch
<murdoch.dun...@gmail.com>wrote:
On 01/05/2013 1:34 PM, Tim Triche, Jr. wrote:
+1 to having runnable code emitted
It does emit runnable code, which is why Herve's complaint was nonsense.
It doesn't emit code of which every substring is runnable.
Duncan Murdoch
patch seems to work nicely, hopefully R-core will agree to apply it to
HEAD
On Wed, May 1, 2013 at 9:45 AM, Paul Johnson <pauljoh...@gmail.com>
wrote:
Whoa.
Don't let my valuable suggestion get lost.
I want "} else {". Yihue wants "} else {". And I have not heard
anybody
say they prefer the other way, unless you interpret Duncan's comment
"that's nonsense" as a blanket defense of the status quo. But I don't
think
he meant that. This is a matter of style consistency and avoidance of
new
R-user confusion and error.
After reading the help for "if", I don't see how anybody can argue
against
this. Good R code has this style:
} else {
and not
}
else
because the latter fails if it is run line-by-line. While trying to
teach
people how to write R programs, it would be nice if the output of
print.function was consistent with the good way, the way that is
actually
practiced in the R source code itself. This is a major source of new
programmer confusion. Its very tough to explain and teach.
pj
--
Paul E. Johnson
Professor, Political Science Assoc. Director
1541 Lilac Lane, Room 504 Center for Research Methods
University of Kansas University of Kansas
http://pj.freefaculty.org http://quant.ku.edu
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