as a fan of S4 i had a look at this; more definitive
replies are undoubtedly to come
> ## now: B00 mother class to B01 and B02, and again B02 "contains" B01 by
> setIs:
> setClass("B00", representation(a="numeric"))
> setClass("B01", representation(a="numeric",b="numeric"), contains= "B00")
the direct specification of containment in the next statement
is important for the dispatch process
> setClass("B02", representation(a="numeric",d="numeric"), contains= "B00")
if we omit the containment assertion your expectations are met
setClass("B02", representation(a="numeric",d="numeric"))
setIs("B02","B01",coerce=function(obj){new("B01", [EMAIL PROTECTED], [EMAIL
PROTECTED])},
replace=function(obj,value){new("B01", [EMAIL PROTECTED], [EMAIL
PROTECTED])})
two diagnostic steps that are illuminating are
getClass("B02") under both approaches (with and without contains="B00"
in definition of B02 class)
and
getMethods("+") under both approaches
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