[R] Google's R Style Guide

[hadley wickham]

But in interactive use the R parser is constrained to work a line at a
time (unless it could predict what you were going to type next ;)

Hadley

On Sat, Aug 29, 2009 at 5:05 PM, John Sorkin<jsorkin at grecc.umaryland.edu> wrote:
> For my money, and perspective as one who has written a compiler, this reflects a failing of the R parser. Both
>
> if (TRUE) {
>     cat("TRUE!!\n")
> }
> else
> {
>     cat("FALSE!!\n")
> }
>
> and
>
>
> if (TRUE)
>  {
>     cat("TRUE!!\n")
>  }
> else
>  {
>     cat("FALSE!!\n")
>  }
>
> are easy to read, and should be accepted as a valid if . . . . else statement.
>
> John
>
>
> John David Sorkin M.D., Ph.D.
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
>>>> Philippe Grosjean <phgrosjean at sciviews.org> 8/29/2009 12:12 PM >>>
> Max Kuhn wrote:
>> Perhaps this is obvious, but Ive never understood why this is the
>> general convention:
>>
>>> An opening curly brace should never go on its own line;
>>
>> I tend to do this:
>>
>> f <- function()
>> {
>>   if (TRUE)
>>     {
>>       cat("TRUE!!\n")
>>     } else {
>>       cat("FALSE!!\n")
>>     }
>> }
>>
>> (I don't usually put one-liners in if/else blocks; here I would have
>> used ifelse)
>>
>> I haven't seen many others format code in this way. Is there an
>> objective reason for this (such as the rule for the trailing "}") or
>> is this just aesthetics?
>
> I think the problem is not much putting the opening brace after
> function(), or after if (...), like you do. The problem is putting the
> else at a new line like in:
>
> if (TRUE) {
>     cat("TRUE!!\n")
> }
> else
> {
>     cat("FALSE!!\n")
> }
>
> When you source this code, the first part until the first closing brace
> is considered complete by the R parser, and then, 'else' is considered
> as the begining of a new command, which is a syntax error:
>
>  > if (TRUE) {
> +     cat("TRUE!!\n")
> + }
> TRUE!!
>  > else
> Error: syntax error
>  > {
> +     cat("FALSE!!\n")
> + }
> FALSE!!
>
> If you put the same code in a function, you got the expected behaviour:
>
>  > f <- function () {
> +     if (TRUE) {
> +         cat("TRUE!!\n")
> +     }
> +     else
> +     {
> +         cat("FALSE!!\n")
> +     }
> + }
>  > f()  # No syntax error!
> TRUE!!
>
> Thus, this is technical reason for NOT putting else on another line.
> For the rest, I share Hadley's feeling that you consumes "too much
> lines" and I tend to prefer the "regular" R syntax you got when you
> source your code.
> Best,
>
> Philippe
>
>
>> Thanks,
>>
>> Max
>>
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>>
>>
>
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