I've found that reference class objects tend to behave like plain old
environments wrt field access, unless a method on e.g. $<- is explicitly
defined.
Here is a code snippet:
library(methods)
Foo <- setRefClass("Foo")
foo <- Foo$new()
foo$a <- 2 # why does this succeed? not a valid field!
## set a silly $<- method
setReplaceMethod("$", "Foo", function(x, name, value) {
callNextMethod(x, "b", value)})
foo$b <- 3
At first, we can set the non-existent field "a" without any error (I don't
think this is the intended behavior). Then we set a silly override on $<-
and things start to behave as expected:
Error in envRefSetField(x, what, refObjectClass(x), selfEnv, value) :
"b" is not a field in class "Foo"
What am I doing wrong?
Thanks,
Michael
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