[BioC] Loading workspace blocks generic function dispach

[Eric Blanc]

I have a workspace which contains a PLMset object (from affyPLM  
package). When I read it, and then load the library affyPLM, I cannot  
visualise the residuals image, while if I load the library first,  
followed by the workspace, the image displays fine. More precisely:

library( affyPLM )
load( "./Image.RData" )
image( Pset, which=1, type="resids" )

works fine, while

load( "./Image.RData" )
library( affyPLM )
image( Pset, which=1, type="resids" )

returns the error:

Error in image.default(Pset, which = 1, type = "resids") :
   argument must be matrix-like

The function existsMethod( "image", "PLMset" ) returns TRUE in the  
first case, and FALSE in the second, while the function  
hasMethod( "image", "PLMset" ) returns TRUE in both cases.

My question is: is there a way to force the display of the image in  
cases where I had loaded the workspace before the library ?

Many thanks,
Eric

PS:
 > sessionInfo()
R version 2.11.0 (2010-04-22)
x86_64-apple-darwin9.8.0

locale:
[1] C

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base

other attached packages:
[1] affyPLM_1.24.0        preprocessCore_1.10.0 gcrma_2.20.0
[4] affy_1.26.1           Biobase_2.8.0

loaded via a namespace (and not attached):
[1] Biostrings_2.16.2 IRanges_1.6.4     affyio_1.16.0     splines_2.11.0

--
Dr Eric Blanc	
Lecturer in Bioinformatics

Tel: +44 (0)20 7848 6532

MRC Centre for Developmental Neurobiology
King's College London
New Hunt's House, Room 4.10B
Guy's Hospital Campus
London SE1 1UL