RMySQL and RPostgreSQL interaction

On Tue, 18 Sep 2012 13:46:06 -0400,
Paul Gilbert <pgilbert902 at gmail.com> wrote:

On 12-09-18 01:30 PM, Sebastian P. Luque wrote:

On Tue, 18 Sep 2012 11:40:26 -0400,
Paul Gilbert <pgilbert902 at gmail.com> wrote:

I am doing some comparison for which I load both RMySQL and
RPostgreSQL from my own packages TSMySQL and TSPostgreSQL and I am
getting the following warning building a vignette. I think with
package namespaces / S4 definitions it is a bit difficult to
generate a self contained example, at least I have not yet managed
to do that, but I would appreciate any suggestions about what needs
to be done.

Loading required package: TSPostgreSQL Loading required package:
RPostgreSQL Warning in .simpleDuplicateClass(def, prev) : A
specification for class "dbObjectId" in package 'RPostgreSQL' seems
equivalent to one from package 'RMySQL' and is not turning on
duplicate class definitions for this class

I've seen this with a vignette using both the maptools and trip
packages, but it was just a warning and the vignette built just fine.

Yes, it is just a warning, and the vignette builds fine. It also looks
like there is probably a simple fix to remove the problem that causes
the warning, since that is what the warning suggests. However, as
Spencer pointed out, isolating a simple example is not so easy.

I had actually built such an example with those packages (available from
CRAN):

---<--------------------cut here---------------start------------------->---
\documentclass{article}
\usepackage{Sweave}

\begin{document}

<<load-packages>>=
library(maptools)
library(trip)

@

\end{document}
---<--------------------cut here---------------end--------------------->---

which produces the warnings:

---<--------------------cut here---------------start------------------->---
     Warning in .simpleDuplicateClass(def, prev) :
      A specification for class ?owin? in package ?trip? seems equivalent to one from package ?maptools? and is not turning on duplicate class definitions for this class
     Warning in .simpleDuplicateClass(def, prev) :
      A specification for class ?ppp? in package ?trip? seems equivalent to one from package ?maptools? and is not turning on duplicate class definitions for this class
     Warning in .simpleDuplicateClass(def, prev) :
      A specification for class ?psp? in package ?trip? seems equivalent to one from package ?maptools? and is not turning on duplicate class definitions for this class
---<--------------------cut here---------------end--------------------->---

Both packages have the same definitions for these classes.  A quick
search on this warning points to
https://stat.ethz.ch/pipermail/r-devel/2011-July/061628.html, which
suggests that adding an importClassesFrom() directive in NAMESPACE and
removing the class definition from one of the packages, might solve
this.  A dependency may be needed though...