[Rd] R 2.3.0: Use of NULL as an environment is deprecated

[Pfaff, Bernhard Dr.]

Dear R-Devel subscriber,

first, let me express my thank to the R-Core team for the new release! I
appreciate their efforts and time spent to enhance R.
In accordance with the 'NEWS' file (see excerpt of it below), 

[...
o	Changed the environment tree to be rooted in an empty
	environment, available as emptyenv().  baseenv() has been
	modified to return an environment with emptyenv() as parent,
	rather than NULL.

...

o	Use of NULL as an environment is deprecated and gives a warning.
...]

I detected the warning message as announced for a couple of contributed
packages, e.g.

library(ape)
library(car)
library(chron)
library(urca)

Now, I am wondering what would be a suitable/elegant way to fix the
packages' code such that the warning does not appear any longer. I am
adressing this question to R-devel, because this might also be of
interest for other package mainatiners.

Many thanks in advance for any hints and pointers.

Regards,
Bernhard




Dr. Bernhard Pfaff
Global Structured Products Group
(Europe)

Invesco Asset Management Deutschland GmbH
Bleichstrasse 60-62
D-60313 Frankfurt am Main

Tel: +49(0)69 298 07230
Fax: +49(0)69 298 07178
Email: bernhard_pfaff at fra.invesco.com 
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