From chiefmurphy at gmail.com  Tue Jul  9 13:03:16 2013
From: chiefmurphy at gmail.com (Dan Murphy)
Date: Tue, 9 Jul 2013 04:03:16 -0700
Subject: [Rd] Is difftime a "class"
Message-ID: <CAHgH9_EJv97fGoiBZoS70MpdotrHwJrp6KJ4NrFXJg-WRjj_UA@mail.gmail.com>

I am trying to write S4 methods with "difftime" in the signature but
am being "informed" (? not a warning or error) that "difftime" is not
a class. Nevertheless, dispatch takes place. Should I simply ignore
that "information"? Here is a toy example:

> setClass("foo", contains = "Date")
> setMethod("+", c("foo", "difftime"), function(e1, e2) callNextMethod())
in method for ?+? with signature ?"foo","difftime"?: no definition for
class ?difftime?
[1] "+"
> x <- new("foo", as.Date("2013-06-30"))
> dt <- as.difftime(1, units = "days")
> x + dt
[1] "2013-07-01"

Thank you,
Dan Murphy



[Rd] Is difftime a "class"
Dan Murphy