A very important point is that library() *had* a 'version' argument for
several years, and this is not what it did. So Mr Williams needs to do
his homework ....
From such a version of R:
version: A character string denoting a version number of the package
to be loaded, for use with _versioned installs_: see the
section later in this document.
...
On 12/04/2012 13:21, Duncan Murdoch wrote:
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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Brian D. Ripley, rip...@stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
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