sys.call(1) will work now, but as my code evolves it tends
towards having more layers of function calls and so the count
given in sys.call(count) has to be altered. This is a maintainance
problem. Sometimes, as when using generic functions, you are
not even aware that the number of calls between two function
calls has changed.
On a more stylistic level, it seems that if the condition system
goes to the trouble of giving you the call as part of the input
to the error handler, why bother finding it in another way?
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
________________________________
From: Sebastien Bihorel [mailto:sebastien.biho...@cognigencorp.com]
Sent: Thursday, January 06, 2011 1:37 PM
To: William Dunlap
Cc: Henrique Dallazuanna; Sebastien Bihorel; R-help
Subject: Re: [R] Stop and call objects
Well, the goal is to include a reference to f2 in the error message
returned by f2('char'); sys.call(1) appears to do the trick. You mentioned this
function could be unreliable, could you please provide an example?
Sebastien
William Dunlap wrote:
-----Original Message-----
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of
Henrique
Dallazuanna
Sent: Wednesday, January 05, 2011 9:26 AM
To: Sebastien Bihorel
Cc: R-help
Subject: Re: [R] Stop and call objects
Try this:
f <- function(x)
tryCatch(sum(x),error=function(e)sprintf("Error in %s:
%s", deparse(sys.call(1)), e$message))
f('a')
The argument e to the error handler contains a call
component so you don't have to rely on the unreliable
sys.call(1) to get the offending call. E.g.,
> f2 <- function(x) {
tryCatch(sum(x),
error=function(e) {
sprintf("Error in %s: %s", deparse(e$call)[1],
e$message)
}
)
}
> f2('char')
[1] "Error in sum(x): invalid 'type' (character) of argument"
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
On Wed, Jan 5, 2011 at 12:23 PM, Sebastien Bihorel <
sebastien.biho...@cognigencorp.com> wrote:
Dear R-users,
Let's consider the following snippet:
f <- function(x)
tryCatch(sum(x),error=function(e) stop(e))
f('a')
As expected, the last call returns an error
message: Error
in sum(x) :
invalid 'type' (character) of argument
My questions are the following:
1- can I easily ask the stop function to
reference the "f"
function in
addition to "sum(x)" in the error message?
2- If not, I guess I would have to extract the
call and
message objects
from e, coerce the call as a character object,
build a
custom string, and
pass it to the stop function using call.=F. How
can I
coerce a call object
to a character and maintain the "aspect" of the
printed
call (i.e. "sum(x)"
instead of the character vector "sum" "x"
returned by
as.character(e$call))?
Thank you
Sebastien
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--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O
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