[R-SIG-Mac] upgradeable R layout

[Alexy Khrabrov]

Greetings -- I'd like to keep my R on Mac in an upgradeable way. I  
noticed that currently all packages I installed from R.app are in the  
R.framework -- are they going to be clobbered when I replace R 2.7.2  
by 2.8.0?

At the same time with the upgrade, I'd also like to switch to 64 bit.   
One good page I found about it is

http://www.matthewckeller.com/html/64_bit_r_on_mac.html

It suggests that packages are installed into a separate directory by  
doing it from command line install.packages with a lib= parameter.

Now I'd like to install everything into a lib anyways, but preferably  
without having to specify lib= all the time -- is there a way to make  
my local location the default for install.packages?

Also -- can the R.app be tweaked to do all this, if I want to use it  
with the 64 bit and local install for packages?

The idea is to make upgrading R smooth -- ideally, it would do  
update.packages(checkBuilt =
TRUE) by itself as a part of the upgrade.

Are there other ways to simplify R upgrade on Mac and/or am I missing  
something?

Cheers,
Alexy