[Rd] dependencies on system packages

[Simon Urbanek]

Claudia,

thanks for you comments .

On Feb 4, 2011, at 3:18 AM, Claudia Beleites wrote:

> Dear all,
> 
> From the writing extensions manual:
> "Other dependencies (external to the R system) should be listed in the ‘SystemRequirements’ field, possibly amplified in a separate README file."
> 
> I guess one problem is the user may not realize that the -dev version is needed, and just sees libxml2 installed but the R package installation stopping with the respective error.
> 

I'd argue that if a user attempts to install a package from sources instead of using the distribution binaries, he should know what he's doing as there is much more involved (proper tools, usually a different library location etc.). And anyone who knows what he's doing also knows that -dev packages are needed (at the latest when the installation fails you remember ;)). If he doesn't then it should give him a clue that he may want to use something else (and especially Linux users should know better ;)).

Clearly, it doesn't prevent users from doing stupid things and I completely agree with you that the README should have the instructions as far as the developer knows. And as a package developer you'll learn soon enough when people start complaining ;).

Thanks,
Simon



> Giving the package name for specific distributions is of course polite (if the developer knows it). As developer you may also put into the README that the package's mailing list/forum/wiki/... contains information and ask the user to enter the package name on his distro if it is not already there.
> 
> 
> my 2 ct
> 
> Claudia
> 
> 
> 
> Am 04.02.2011 04:48, schrieb Simon Urbanek:
>> Jeroen,
>> 
>> On Feb 3, 2011, at 9:31 PM, Jeroen Ooms wrote:
>> 
>>> 
>>> Many R packages depend on some unix libraries that are not part of most
>>> default installations. I often spend a significant amount of time figuring
>>> out where to get the appropriate libraries for compiling these packages,
>>> after they give some vague error of something missing. I was wondering why
>>> there is no formal system of specifying non-R dependencies in the
>>> DESCRIPTION file. If this would be the case, then during the installation of
>>> an R package, the user could be prompted to install required system packages
>>> (if they have appropriate privileges).
>>> 
>>> So for example:
>>> 
>>> Package: XML
>>> Version: 3.2-0
>>> Depends: R (>= 1.2.0), methods, utils
>>> Depends-debian: libxml2-dev
>>> Depends-ubuntu: libxml2-dev
>>> Depends-redhat: libxml2-devel
>>> Depends-suse: libxml2-devel
>>> etc.
>>> 
>>> This might make life for many people just a little easier. If they are root
>>> and the package is in their system repositories, than it will install
>>> automatically. If not, at least they know for which package to look, or
>>> request their sys admin to install.
>> 
>> Well, there is already such system in place and it is the corresponding descriptions in the distributions. Obviously as an author of the package I don't care what any particular Linux distribution uses as a name for the needed dependencies as the corresponding chaos is distribution-specific. The only person who can reasonably determine the dependencies is the maintainer of the distribution and that's what they do and as a user of the above mentioned distributions you should be thankful to them. Fortunately, normal users don't have to worry about it as major distributions already come with a large set of R packages resolving all dependencies. Hence I don't see any reason why this should have anything to do with the DESCRIPTION file. The improvements I could think of would be a parseable entry or a canonical pointer to dependency sources, but that's a whole another story.
>> 
>> Cheers,
>> Simon
>> 
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