The options showWarnCalls and showErrorCalls may also help --
they can be use do enable automatic printing of a call stack
summary. From ?options:
‘showWarnCalls’, ‘showErrorCalls’: a logical. Should warning and
error messages show a summary of the call stack? By default
error calls are shown in non-interactive sessions.
Best,
luke
On 02/04/2011 10:09 AM, William Dunlap wrote:
-----Original Message-----
From: r-help-boun...@r-project.org
[mailto:r-help-boun...@r-project.org] On Behalf Of Duncan Murdoch
Sent: Friday, February 04, 2011 6:03 AM
To: Ernest Adrogué
Cc: r-h...@stat.math.ethz.ch
Subject: Re: [R] get caller's name
On 03/02/2011 10:27 AM, Ernest Adrogué wrote:
Hi,
Suppose a function that checks an object:
stop.if.dims<- function(x) {
if (! is.null(dim(x))) {
stop("cannot handle dimensional data")
}
}
This would be used by other functions that can only work with
dimensionless objects. The problem is the error message
would need to
include the name of the function that called stop.if.dims,
so that the
user knows which function got an argument that was incorrect.
How do I do this? Or maybe there is another way...
I see you have the answer you wanted, but I'd suggest you don't need
this: the user should just use traceback() after the error
to see the
full call stack. Perhaps it's not the caller that's the problem, but
the caller of the caller...
Duncan Murdoch
stopifnot() deals with the problem by arranging for the
error reporting mechanism not to say what function the
error comes from. If you are in the know, not seeing
"Error in someFunction(arg):" in the error might motivate
you to call traceback(). If you are not in the know, it
just frustrates you.
R> myFunc<- function(x) stopifnot(all(x>0))
R> myFunc(-pi)
Error: all(x> 0) is not TRUE
R> traceback()
3: stop(paste(ch, " is not ", if (length(r)> 1L) "all ", "TRUE",
sep = ""), call. = FALSE)
2: stopifnot(all(x> 0))
1: myFunc(-pi)
In S+ stopifnot() uses eval(call("stop", message), sys.parent())
to make the error message appear to come from the caller of
stopifnot(). The initial message is clearer but the traceback
more confusing:
> myFunc<- function(x) stopifnot(all(x>0))
> myFunc(-pi)
Problem in myFunc( - pi): all(x> 0) is not TRUE
Use traceback() to see the call stack
> traceback()
8: eval(action, sys.parent())
7: doErrorAction("Problem in myFunc( - pi): all(x> 0) is not TRUE", 1000)
6: stop("all(x> 0) is not TRUE")
5: eval(call, sys.parent())
4: stopifnot(all(x> 0))
3: myFunc( - pi)
2: eval(expression(myFunc( - pi)))
1:
Message: Problem in myFunc( - pi): all(x> 0) is not TRUE
If I try the eval(call("stop",message), sys.parent()) trick
in R the error is reported as being from eval():
> myFunc(-pi)
Error in eval(expr, envir, enclos) : all(x> 0) is not TRUE
S+'s error handler has some logic so that a stop() called from
eval() is reported as being from the frame that eval is evaluating
in.
It might be nice to be able to tell stop(), warning(), and message()
to pretend they were called from somewhere other than where they
were actually called from. Falling back on traceback() doesn't
help with warnings and messages. Being able to put standard messages
like 'x not a matrix' into utility functions is handy, but it makes
it hard to track down the problem.
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
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and provide commented, minimal, self-contained, reproducible code.
______________________________________________
R-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
--
Luke Tierney
Statistics and Actuarial Science
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: l...@stat.uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
