[Rd] Extending type list: names and inherited methods issue

From: Renaud Gaujoux <renaud_at_mancala.cbio.uct.ac.za>
Date: Fri, 04 Mar 2011 13:30:02 +0200


Hi,

I want to extend the type list, but it looks like the names are not handled properly (in the show method), not the [ method. See below for code example.
I imagine this comes from the S3/S4 mixing, but I would like to understand and the recommended work around (that avoid redefining all the list methods [, $, etc...).
Thank you.

Bests,
Renaud

# define S4 class that inherits from list
setClass('A', contains='list')

# nothing to say when one creates an object with an unnamed list
x <- new('A', list(1,2,3))
x

# set the names: seems ok but they are not printed
names(x) <- letters[1:3]
names(x)
x
# same thing if one put the S3 .Data slot
names(x@.Data) <- letters[4:6]
names(x)
x

# the subsetting works but returns a list instead of the expected object
of class A
class(x[1])

 > sessionInfo()
R version 2.12.1 (2010-12-16)
Platform: x86_64-pc-linux-gnu (64-bit)

locale:

  [1] LC_CTYPE=en_ZA.utf8       LC_NUMERIC=C              
LC_TIME=en_ZA.utf8        LC_COLLATE=en_ZA.utf8     
LC_MONETARY=C             LC_MESSAGES=en_ZA.utf8    LC_PAPER=en_ZA.utf8
  [8] LC_NAME=C                 LC_ADDRESS=C              
LC_TELEPHONE=C            LC_MEASUREMENT=en_ZA.utf8 LC_IDENTIFICATION=C

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

-- 
Renaud Gaujoux
Computational Biology - University of Cape Town
South Africa


 

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