From murdoch.duncan at gmail.com  Thu Apr 12 14:21:48 2012
From: murdoch.duncan at gmail.com (Duncan Murdoch)
Date: Thu, 12 Apr 2012 08:21:48 -0400
Subject: [Rd] [patch] giving library() a 'version' argument
In-Reply-To: <21A5E1E970CD46459ECBE86D6CC4B28C667AA79C@spexch01.WindLogics.local>
References: <21A5E1E970CD46459ECBE86D6CC4B28C667AA79C@spexch01.WindLogics.local>
Message-ID: <4F86C8DC.7020608@gmail.com>

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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[Rd] [patch] giving library() a 'version' argument
Duncan Murdoch