[Rd] particulars of importing/loading libraries

[Sklyar, Oleg (London)]

Sorry Simon, you are right. I tried to recreate a problem that I had
with other packages where the packages were added to Depends but made a
mistake. However the problem remains if I do the following.

Added: pack1 to Depends of pack2. Now I create pack3 with the following
contents: it does not import pack1 directly, nor depends on it. It
rather imports pack2 and depends on pack2. I then expect the
functionality of pack1 to be available still if I only load pack3. But I
now get errors with pack3 calling the function from pack1. Does this
mean I need to import and depend on pack1 and methods explicitly in
pack3. I.e. do I have to import and depend on ALL the packages that may
be in use, even if they are imported by other that I depend on and
import:

---- pack3: DESCRIPTION -----

Package: pack3
Version: 0.0.1
Date: 12 Jan 2009
Title: pack1 to test S3/S4 methods compatibility
Author:  Oleg Sklyar
Depends: R (>= 2.7.1), pack2
Maintainer: Oleg Sklyar <osklyar at maninvestments.com>
Description: pack3
LazyLoad: yes
License: Proprietary
URL: http://www.maninvestments.com
LazyLoad: no

---- pack3: NAMESPACE ------
import(pack2)
exportPattern("^[^\\.]")

---- pack3: posix.R ------
testPosix2 = function() {
    z = as.POSIXct(testPosixVal)
    print(z)
    print(class(z))
    z
}

Note, that the above function is the same as in pack2, just a different
name.


*** R 2.9.0 (svn -r 46585) [/share/research/R-devel/20081002/lib64/R]
***
> library(pack3)
Loading required package: pack2
Loading required package: pack1
> as.POSIXct(pack1::testPosixVal)
[1] "2009-01-13 15:29:50 UTC"
> testPosxi() ## called from pack2
[1] "2009-01-13 15:29:50 UTC"
[1] "POSIXt"  "POSIXct"
[1] "2009-01-13 15:29:50 UTC"
> testPosix2() ## called from pack3
Error in as.POSIXct.default(testPosixVal) : 
  do not know how to convert 'testPosixVal' to class "POSIXlt"




Dr Oleg Sklyar
Research Technologist
AHL / Man Investments Ltd
+44 (0)20 7144 3107
osklyar at maninvestments.com 

> -----Original Message-----
> From: Simon Urbanek [mailto:simon.urbanek at r-project.org] 
> Sent: 14 January 2009 01:51
> To: Sklyar, Oleg (London)
> Cc: r-devel at r-project.org
> Subject: Re: [Rd] particulars of importing/loading libraries
> 
> Oleg,
> 
> On Jan 13, 2009, at 11:00 , Sklyar, Oleg (London) wrote:
> 
> > Dear List:
> >
> > Sorry for posting maybe a trivial question, but I have a basic
> > understanding problem. If I have say pack1 and pack2, two R 
> packages,
> > and pack2 depends on and imports pack1 fully (as in the 
> code below),  
> > is
> > there a way to make all the functionality of pack1 available for the
> > global and other environments (not only for the functions 
> called from
> > withing pack2) by loading pack2 only? I thought if pack2 
> depends on  
> > and
> > imports pack1 and essentially reexports everything, one 
> should get the
> > full functionality simply by loading pack2. This does not 
> seem to be  
> > the
> > case or I am missing something trivial in my NAMESPACE/DESCRIPTION
> > files?
> >
> > If this is documented in Writing R Extensions, I would be thankful  
> > for a
> > page number and maybe a quick fix in my example below as so 
> far I have
> > not been able to find a clear explanation.
> >
> > The problem can be illustrated by the following simple 
> example (this  
> > is
> > a simple code for 2 packages, pack1 and pack2; plus an example).
> >
> 
> if you bothered to use R CMD check you would find your bug right away:
> * checking package dependencies ... ERROR
> Namespace dependencies not required:
>    pack1
> 
> You simply forgot to add pack1 to the Depends: line - that's 
> all. Once  
> you fix that, you'll see what happens:
> 
>  > library(pack2)
> Loading required package: pack1
>  > as.POSIXct(pack1::testPosixVal)
> [1] "2009-01-14 01:38:08 UTC"
> 
> Cheers,
> S
> 
> 
> > Thank you for your replies.
> >
> > Dr Oleg Sklyar
> > Research Technologist
> > AHL / Man Investments Ltd
> > +44 (0)20 7144 3107
> > osklyar at maninvestments.com
> >
> > --- pack1: DESCRIPTION ------
> > Package: pack1
> > Version: 0.0.1
> > Date: 12 Jan 2009
> > Title: pack1 to test S3/S4 methods compatibility
> > Author:  Oleg Sklyar
> > Depends: R (>= 2.7.1), methods
> > Maintainer: Oleg Sklyar <osklyar at maninvestments.com>
> > Description: pack1
> > LazyLoad: yes
> > License: Proprietary
> > URL: http://www.maninvestments.com
> > LazyLoad: no
> >
> > --- pack1: NAMESPACE ------
> > import(methods)
> > exportPattern("^[^\\.]")
> > exportClasses(posixTime)
> > exportMethods(as.POSIXct)
> >
> > --- pack1: posix.R ------
> > setClass("posixTime", "numeric")
> >
> > setGeneric("as.POSIXct")
> > setMethod("as.POSIXct", signature(x="posixTime"),
> >    function(x, tz) {
> >        z = x at .Data
> >        attr(z,"class") = c("POSIXt", "POSIXct")
> >        attr(z,"tzone") = "UTC"
> >        z
> >    }
> > )
> >
> > testPosixVal = new("posixTime", as.numeric(Sys.time()))
> >
> > --- pack2: DESCRIPTION
> > Package: pack2
> > Version: 0.0.1
> > Date: 12 Jan 2009
> > Title: pack2 to test S3/S4 methods compatibility
> > Author:  Oleg Sklyar
> > Depends: R (>= 2.7.1), methods
> > Maintainer: Oleg Sklyar <osklyar at maninvestments.com>
> > Description: pack2
> > LazyLoad: yes
> > License: Proprietary
> > URL: http://www.maninvestments.com
> > LazyLoad: no
> >
> > --- pack2: NAMESPACE ------
> > import(pack1)
> > exportPattern("^[^\\.]")
> >
> > --- pack2: posix.R ------
> > testPosix = function() {
> >    z = as.POSIXct(testPosixVal)
> >    print(z)
> >    print(class(z))
> >    z
> > }
> >
> > ------ test code to run from global env, showing problems -------
> > require(pack2)
> >
> > ## use as.POSIXct imported into pack2 from pack1 to do the  
> > conversion in
> > the fun
> > testPosix()
> > #~ [1] "2009-01-13 15:29:50 UTC"
> > #~ [1] "POSIXt"  "POSIXct"
> > #~ [1] "2009-01-13 15:29:50 UTC"
> >
> > ## now try using it directly from the global env (pack1 was not
> > explicitly loaded)
> > as.POSIXct(pack1::testPosixVal)
> > #~ Error in as.POSIXct.default(pack1::testPosixVal) :
> > #~  do not know how to convert 'pack1::testPosixVal' to class  
> > "POSIXlt"
> >
> > ## now require pack1 explicitly and try again
> > require(pack1)
> > as.POSIXct(pack1::testPosixVal)
> > #~ [1] "2009-01-13 15:29:50 UTC"
> >
> >
> > 
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> 
> 

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