On 04/22/2016 04:38 PM, Boylan, Ross wrote:
It seems that if an S4 class has no slots it can't be instantiated because it
is assumed to be virtual. Is there a way around this other than adding a
do-nothing slot? A singleton would be OK, though is not essential.
Problem:
EmptyFitResult <- setClass("EmptyFitResult", representation=representation())
# also tried it without the second argument. same result.
> e <- EmptyFitResult()
Error in new("EmptyFitResult", ...) :
trying to generate an object from a virtual class ("EmptyFitResult")
This in R 3.1.1.
Context:
I fit simulated data; in some simulations none survive to the second stage of
fitting. So I just need a way to record that this happened, in a way that
integrates with my other non-null results.
A not too artificial solution is to create a base class, with derived
classes corresponding to stateless or stateful conditions
Base = setClass("Base"); A = setClass("A", contains="Base"); A()
Martin Morgan
Thanks.
Ross Boylan
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