[Rd] Attributes of top level environments clobbered (was Re: [R] possible bug in function 'var' in R 2.7.2?)

Luke Tierney luke at stat.uiowa.edu
Fri Oct 3 17:43:07 CEST 2008

I will look into fixing it sometime if no one else feels like doing
it.  The environment aspect is not high priority; some other related
issues are more so (locking and active bindings as I recall).  But
even thoughs may not make it to the top of my queue any time soon.

The issue of placing attributes on environments has come up before,
many times.  It is routinely advised against.  For better or worse,
the way environments were exposed to the R level is not designed to
support this properly.  Fixing this so that attributes are supported
reliably is non-trivial, and it is hard to justify the effort given
that there are standard work-arounds (such as putting the environment
in a list and attaching attributes to the list).  An alternative way
of removing the issues associated with attributes on environments, in
line with the way NULL works, is to disable placing attributes on
environments, at least from the R level.  This option is looking
increasingly attractive.


On Fri, 3 Oct 2008, Gabor Grothendieck wrote:

> On Fri, Oct 3, 2008 at 3:23 AM, Martin Maechler
> <maechler at stat.math.ethz.ch> wrote:
>> a much better (and much less error-prone) idea would be to install
>> R 2.8.0 alpha  even now.
>> It will become 'beta' early next week.
>> We are asking the R community to please install and use
>> pre-release versions of R  (if you can / are allowed to)
>> at least from beta onwards, and report problems you see early on
>> *before* the final release.
> The bug discussed in the following year-old post suggested that
> the problem of clobbering attributes of top level environment objects
> would be fixed for 2.7 but its still in R version 2.7.2 (2008-08-25)"
> and also still in  "R version 2.8.0 alpha (2008-10-01 r46589)"
>   https://stat.ethz.ch/pipermail/r-devel/2007-October/047184.html
> The Avoiding R Bugs section of this page:
>   http://r-proto.googlecode.com
> has more discussion as well as a list of some other R bugs.
> This can be tested by creating a package with these two files only:
> Package: testlazy
> Version: 1.0-0
> Date: 2008-10-03
> Title: Test lazy loading
> Author: G Grothendieck
> Maintainer: G Grothendieck <ggrothendieck at gmail.com>
> Description: Test lazy loading with top level objects.
> Depends: proto
> LazyLoad: yes
> License: GPL-2
> ---R/testlazy.R---
> TopLevel <- proto()
> ---
> And then testing it:
> library(testlazy)
> class(TopLevel)
> If its class is "environment" only then the class attribute was stripped.
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Luke Tierney
Chair, 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:      luke at stat.uiowa.edu
Iowa City, IA 52242                 WWW:  http://www.stat.uiowa.edu

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