On Mon, 9 Oct 2006, Prof Brian Ripley wrote:
> On Fri, 6 Oct 2006, Luke Tierney wrote:
>
>> On Fri, 6 Oct 2006, Duncan Murdoch wrote:
>>
>>> On 10/6/2006 9:05 AM, [EMAIL PROTECTED] wrote:
>>>> Full_Name: Thomas Friedrichsmeier
>>>> Version: 2.4.0
>>>> OS: GNU/Linux
>>>> Submission from: (NULL) (84.61.116.51)
>>>>
>>>>
>>>> Since R 2.4.0, operator "::" also returns objects in the package
>>>> environment, if
>>>> the package does not have a namespace. This is a very welcome addition.
>>>>
>>>> Additional wish:
>>>> If a package has a namespace, but does not place all symbols in that
>>>> namespace,
>>>> lookup will still fail. For example in package boot (version 1.2-26):
>>>>
>>>> library (boot)
>>>> exists ("motor", envir=as.environment ("package:boot")) # TRUE
>>>> getAnywhere ("motor") # found in
>>>> package:boot
>>>> boot::motor # error not in
>>>> namespace
>>>>
>>>> This is as documented, but I think it would be convenient, if boot::motor
>>>> would
>>>> also return the object in this case.
>>>
>>> At first I was ready to disagree with you, telling you to use the ":::"
>>> operator for something that is not exported: but in fact motor is a
>>> dataset, so it is exported from the package by being loaded into the
>>> package environment when the package is loaded. I agree that the "::"
>>> operator should find it.
>>
>> It might be a good idea to rethink the decision to have data be
>> handled specially instead of having data sets be treated as ordinary
>> exported variables. There may be a good reason for doing what we do
>> now but I don't know what it is. If there really is a good reason to
>> continue this then maybe we should think about this addition. It
>> doesn't feel like the right thing to do but may be harmless.
>
> The reason was (and is) that if datasets are in the namespace, functions in
> the namespace find them ahead of a dataset of the same name in the user's
> workspace. (This broke the MASS scripts, for example, and also affects car.)
> (We do have a mechanism to put system datasets in the namespace where this is
> the desired behaviour, but it seems uncommon.) I really don't fancy
> explaining to our beginning students that when they are asked to correct some
> entries in a dataset some functions will see the corrected version and some
> the original if they just use fix().
This behavior does not seem desireable. Can you give specific
examples?
Best,
luke
--
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: [EMAIL PROTECTED]
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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