On 12/02/2009 7:01 AM, Romain Francois wrote:
Hello,Consider this file (/tmp/test.R) : <file> f <- function( x, y = 2 ){ z <- x + y print( z ) } </file> I get this in R 2.7.2 : > p <- parse( "/tmp/test.R" ) > str( attr( p, "srcref" ) ) List of 1 $ :Class 'srcref' atomic [1:4] 1 1 4 1 .. ..- attr(*, "srcfile")=Class 'srcfile' length 4 <environment> and this in R-devel : > p <- parse( "/tmp/test.R" ) > str( attr(p, "srcref") ) List of 1 $ :Class 'srcref' atomic [1:6] 1 1 4 1 1 1 .. ..- attr(*, "srcfile")=Class 'srcfile' <environment: 0x946b944> What are the two last numbers ?
The original design for srcref gave 4 entries: start line, start byte, stop line, stop byte. However, in multibyte strings, bytes don't correspond to columns, so error messages could often report the wrong location according to what a user sees in an editor. To support the more useful error messages in R-devel, I added two more values: start column and stop column. With pure ASCII text these will be the same as start byte and stop byte; with UTF-8 text and non-ASCII characters they will be be different. Other multibyte encodings are only supported if the platform can convert them to UTF-8 (and are not well tested; error reports would be welcome, if there's a way to improve the performance.)
If you are using these for error reports, I recommend using the two new values. If you are trying to retrieve the text from the source file, use the originals.
Duncan Murdoch ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
