Yohan Chalabi wrote:
Dear all,
In R-devel I have noticed the new approach for the "ts" class in the
package "methods".
the "structure" behaviour of "ts" is not always kept when one uses
"ts" objects and objects of classes which extend the virtual class
"structure".
As a short example:
## this works fine
setClass("foo", representation(header = "character"), contains = "structure")
foo <- new("foo", 1:10, header = "foo")
ts <- ts(1:10)
foo / ts
## but the problem appears when one defines an "Ops" method for class "foo"
setMethod("Ops", c("foo", "foo"),
function(e1, e2) {
.Data <- callGeneric([EMAIL PROTECTED], [EMAIL PROTECTED])
header <- paste([EMAIL PROTECTED], [EMAIL PROTECTED], sep = "_")
new("foo", .Data, header = header)
})
foo <- new("foo", 1:10, header = "foo")
foo + foo
ts <- ts(1:10)
foo / ts
# Error in getDataPart(1:10) : no '.Data' slot defined for class "ts"
Is this the expected behavior?
No, not expected. It may take some special treatement to fix it, though.
Your subject heading is indeed the problem. Normally, the structure of
an S3 class is a black box, and no S4 slots should usually be associated
with it when it's registered via setOldClass.
However, just because "ts" does want to be a "structure" class, it would
be nice to give it a .Data slot. I'll experiment with this and see if
it causes other things to break immediately.
Thanks for the report.
John Chambers
regards,
Yohan
--
PhD student
Swiss Federal Institute of Technology
Zurich
www.ethz.ch
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