[Rd] scoping goes wrong when some functions are used within others.

Erik Iverson eriki at ccbr.umn.edu
Fri Oct 1 19:21:55 CEST 2010

Joris Meys wrote:
> Dear,
> I'm following the r tag on stackoverflow.com, and couldn't but notice
> there are quite some questions popping up that deal with scoping in
> relation to custom functions. I grinded my teeth on it already, and I
> have absolutely no clue what goes wrong. The general pattern is as
> follows :
> ff <- function(x){
>     y <- some_value
>     some_function(y)
> }
>> ff(x)
> Error in eval(expr, envir, enclos) : object 'y' not found

I get:

Error in ff(x) : object 'some_value' not found

which is entirely consistent, since it has not been bound to a value.

> I tried to report this as a bug earlier, but got the message I used
> the wrong channel. I also don't know how to formalize it into a bug
> report on the report site. That's why I bring it to your attention
> this way, and want to ask you whether this is by design and we're all
> doing something wrong, whether these are problems within certain
> packages/situations, ...
> I solve these problems now by adding an environment to my global
> environment, and delete it after the function finished running. But
> this can't be the correct way.
> The problem is described here :
> http://stackoverflow.com/questions/3840769/scoping-and-functions-in-r-2-11-1-whats-going-wrong
> Links to different reports, all having that same pattern but with
> different functions :
> http://stackoverflow.com/questions/3742415/r-statistical-scoping-error-using-transformby-part-of-the-doby-package
> http://stackoverflow.com/questions/3768417/how-to-use-acast-reshape2-within-a-function-in-r
> http://stackoverflow.com/questions/3661500/why-cant-i-pass-a-dataset-to-a-function
> http://stackoverflow.com/questions/3574858/values-not-being-copied-to-the-next-local-environment
> http://stackoverflow.com/questions/2646402/using-functions-and-environments

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