Got it. Thanks very much. On 5/28/07, Prof Brian Ripley <[EMAIL PROTECTED]> wrote: > How about 'traceback'? (It does not necesssarily show all the frames, but > it does help and the exceptions are fairly esoteric.) > > On Mon, 28 May 2007, ronggui wrote: > > > In that "the meaning of parent.frame depends on where it is > > evaluated", is there a nice way to figure out which frame an express > > is evaluated? for example, I would like to konw what does > > parent.frame(2) refer to. > > > >> f1 <- function(x,digits=5) lapply(x, f2) > >> f2 <- function(x) evalq(print(x+1,digits=digits),list(x=x),parent.frame(2)) > >> f1(list(x1=1)) > > Error in print.default(x + 1, digits = digits) : > > object "digits" not found > > > > > > On 5/27/07, Prof Brian Ripley <[EMAIL PROTECTED]> wrote: > >> The meaning of parent.frame depends on where it is evaluated. So one > >> should not expect it to do the same thing in two equivalent expressions > >> (and nor should one expect deparse to do so, for example). > >> > >> A pretty close analogy is that using a symbolic link in a file system is > >> equivalent to using the original file path, at least until you try '..' or > >> 'pwd' on the path. (In the case of 'pwd' it depends on the OS: POSIX > >> only requires '_an_ absolute pathname'.) > >> > >> On Sun, 27 May 2007, ronggui wrote: > >> > >> > The help page of eval says: The 'evalq' form is equivalent to > >> > 'eval(quote(expr), ...)'. But the following is not equivalent. Can > >> > anyone give me some explaination? Thanks very much. > >> > > >> >> f1 <- function(x,digits=5) lapply(x, f2) > >> >> f2 <- function(x) > >> eval(quote(print(x+1,digits=digits)),list(x=x),parent.frame(2)) > >> >> f1(list(x1=1)) > >> > [1] 2 > >> > $x1 > >> > [1] 2 > >> > > >> >> > >> >> f1 <- function(x,digits=5) lapply(x, f2) > >> >> f2 <- function(x) > >> evalq(print(x+1,digits=digits),list(x=x),parent.frame(2)) > >> >> f1(list(x1=1)) > >> > Error in print.default(x + 1, digits = digits) : > >> > object "digits" not found > >> > >> -- > >> Brian D. Ripley, [EMAIL PROTECTED] > >> Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > >> University of Oxford, Tel: +44 1865 272861 (self) > >> 1 South Parks Road, +44 1865 272866 (PA) > >> Oxford OX1 3TG, UK Fax: +44 1865 272595 > >> > > > > > > > > -- > Brian D. Ripley, [EMAIL PROTECTED] > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 >
-- Ronggui Huang Department of Sociology Fudan University, Shanghai, China ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.