On 12-04-11 11:28 AM, Ken Williams wrote:
I've made a small enhancement to R that would help developers better control
what versions of code we're using where. Basically, to load a package in R,
one currently does:
library(whateverPackage)
and with the enhancement, you can ensure that you're getting at least version X
of the package:
library(whateverPackage, version=3.14)
Reasons one might want this include:
* you know that in version X some bug was fixed
* you know that in version X some feature was added
* that's the first version you've actually tested it with& you don't want
to vouch for earlier versions without testing
* you develop on one machine& deploy on another machine you don't control,
and you want runtime checks that the sysadmin installed what they were supposed to
install
I don't really see the need for this. Packages already have a scheme
for requiring a particular version of a package, so this would only be
useful in scripts run outside of packages. But what if your script
requires a particular (perhaps obsolete) version of a package? This
change only puts a lower bound on the version number, and version
requirements can be more elaborate than that.
I think my advice would be:
1. Put your code in a package, and use the version specifications there.
2. If you must write it in a script, then put a version test at the
top, using packageVersion().
Duncan Murdoch
In general, I have an interest in helping R get better at various things that would help
it play in a "production environment", for various values of that term. =)
The attached patch is made against revision 58980 of
https://svn.r-project.org/R/trunk . I think this is the first patch I've
submitted to the R core, so please let me know if anything's amiss, or of
course if there are reservations about the approach.
Thanks.
--
Ken Williams, Senior Research Scientist
WindLogics
http://windlogics.com
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