On Nov 22, 2007 4:14 PM, Gabor Grothendieck <[EMAIL PROTECTED]> wrote: > The SystemRequirements field on the DESCRIPTION file is used > to document the system requirements. For example, the DESCRIPTION > file for Ryacas (which requires yacas) is shown below. > > Package: Ryacas > Version: 0.2-8 > Date: 2007-08-22 > Title: R interface to the yacas computer algebra system > Author: Rob Goedman <[EMAIL PROTECTED]>, Gabor Grothendieck > <[EMAIL PROTECTED]>, Søren Højsgaard > <[EMAIL PROTECTED]>, Ayal Pinkus <[EMAIL PROTECTED]> > Maintainer: G Grothendieck <[EMAIL PROTECTED]> > Encoding: latin1 > Description: An interface to the yacas computer algebra system. > Depends: R (>= 2.5.1), XML > SystemRequirements: yacas (>= 1.0.63) # instructions on home page > License: GPL > URL: http://ryacas.googlecode.com
Thats very useful to know and something that I wasn't aware of. But (in my mind) there is a subtle difference between installing packages that require specific libraries and those that require a specific piece of software. Taking the Ryacas package as an example, anyone installing that would automatically know that its required, and in all likelihood would probably have it installed on their system already and have been using it but then decided they want to interface with it from R. This isn't necessarily the case with libraries, you wouldn't know that a dependency is required until you come to try and install the package and get error messages that something is missing. There is also the rather striking difference (taking the two packages that have been discussed) in that Ryacas will install on a system that doesn't have the SystemRequirement met (i.e. without yacas installed) whereas GDD won't install unless the system has the SystemRequirement (libgd) is installed, and it is this problem that I am trying to help address. I do realise that in either instance a user could find this out in advance of installing any package by simply reading the DESCRIPTION file. I suspect that the ultimate answer to the question that I'm asking (i.e. how can dependencies for CRAN packages be pulled in *automatically* when installing them) will simply be that its down to the user/sysadmin to sort this out. Neil -- "Don't remember what you can infer." - Harry Tennant Email - [EMAIL PROTECTED] / [EMAIL PROTECTED] Website - http://slack.ser.man.ac.uk/ Photos - http://www.flickr.com/photos/slackline/ ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
