On 12-02-06 3:11 PM, Francois Rousseu wrote:
>
> Hello useRs
> I am looking for a function that can give the list of lines that were evaluated or used to generatethe last output from any function, whether an error message was generated or not. For example, let's say I have a function like this:
> foo<- function( x ){ if( x>10 ){ ans<- x+100 }else{ ans<- x-100 } ans }
> and I type:
>> foo(4)[1] -96
> I would like a function that returns something like this
> list.lines(foo)[1] 1 3 4 5 6
> or:
>> foo("hello")Error in x + 100 : non-numeric argument to binary operator
> list.lines(foo)[1] 1 2
> Is there already a function in R doing something similar or anybody has any hints for functions that I could use to create such a function?
> Sincerely,Francois Rousseu
There isn't a function like that. I think it would be hard to write one
without internal changes to R, but those changes might not have to be
too large if the function had srcref information included, because the
evaluator does have access to that.
(One way to do it without changing R is to pre-process the function to
add in lots of extra code that records where it is as it is being
evaluated. This is a little tricky to get right, but it might be
quicker than waiting for the internal changes.)
Duncan Murdoch