[R] assign / environment side effect on R 2.4.0

[Prof Brian Ripley]

Please do study the posting guide, as there is no `R 2.4.0'.

This seems to be related to the NEWS item

     o	[[ on a list does not duplicate the extracted element unless
 	necessary.  (It did not duplicate in other cases, e.g. a
 	pairlist.)

Now in so far as I can follow it, in your example [[ behaves in the same 
way as $ always did (which is what informed people would expect).

R-help is not the place to discuss unreleased versions of R, nor for 
questions about code development.  (Did I mention studying the posting 
guide?)


On Fri, 23 Jun 2006, Thomas Petzoldt wrote:

> Sorry,
>
> the posted example had the side effect on all platforms (correctly: R
> 2.2.1/Windows, 2.3.1/Linux, 2.4.0/Windows), but in the following
> corrected example the behavior of 2.4.0 differs from the older versions.
>
> The only difference between the "wrong" and the "new" example is
> L[["test"]] vs. L$test in the assign.
>
> Thomas P.
>
>
> envfun <- function(L) {
> #  L <- as.list(unlist(L))
>  p <- parent.frame()
>  assign("test", L[["test"]], p) ## [["test"]] instead of $test
>  environment(p[["test"]]) <- p
> }
>
>
> solver <- function(L) {
>  envfun(L)
>  # some other stuff
> }
>
> L <- list(test = function() 1 + 2)
>
> e1 <- environment(L$test)
> solver(L)
> e2 <- environment(L$test)
>
> print(e1)
> print(e2)
>
> ______________________________________________
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> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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