[Rd] The case for freezing CRAN

[Therneau, Terry M., Ph.D.]

This has been a fascinating discussion.

Carl Boettinger replied with a set of examples where the world is much more fragile than 
my examples.  That was useful.  It seems that people in my area (medical research and 
survival) are more careful with their packages (whew!).

Gabor Csardi discussed the problems with maintaining a package with lots of dependencies.
I maintain the survival package which currently has 246 reverse dependencies and take a 
slightly different view, which could be described as "the price of fame".  I feel a 
responsiblity to not break R.  I have automated scripts which download the latest copy of 
all 246, using the install-tests option, and run them all. Most updates have 1-3 issues.  
About 25% of the time it turns out to be a problem that I introduced, and in all the 
others I have found the other package authors to be responsive.  It is a nuisance, yes, 
but also worth it.  I've built the test scripts over several years, with help from several 
others; a place to share this information would be a useful addition.

This process also keeps me honest about any updates that are not backwards compatable.  
There is hardly a single option that is not used by some other package, somewhere.

Terry Therneau