Strange behavior of assign in a S4 method.
Dear Christophe
type
showMethods("foo1", inc=TRUE)
showMethods("foo2", inc=TRUE)
to see the difference between the two functions, and this will explain
their different behaviour. This feature of S4 has been discussed here
many times before, see e.g.:
http://tolstoy.newcastle.edu.au/R/e4/help/08/01/1676.html
Perhaps juggling with the 'n' argument of 'parent.frame' could help in
hacking something together that 'works', but as far as I can see what
you want to is an abuse of R's pass by value / functional language
semantics.
For example, try these and check whether this results in what you intended:
foo2(3)
foo2(e+2)
sapply(1:5, foo2)
ls()
Best wishes
Wolfgang
Christophe Genolini scripsit 15/03/10 11:33:
Hi the list,
I define a method that want to change an object without assignation
(foo(x) and not x<-foo(x)) using deparse and assign.
But when the argument of the method does not match *exactly* with the
definition of the generic function, assign does not work...
Anything wrong?
Christophe
#------ Does not work ------#
setGeneric("foo1",function(x,...){standardGeneric("foo1")})
setMethod(f="foo1",signature="numeric",definition=
function(x,y=1,...){
nameX<-deparse(substitute(x))
x <- x^2
assign(nameX,x,envir=parent.frame())
}
)
e <- 3
foo1(e,y=5)
cat(e)
#------ Does work ------#
setGeneric("foo2",function(x,...){standardGeneric("foo2")})
setMethod(f="foo2",signature="numeric",definition=
function(x,...){
nameX<-deparse(substitute(x))
x <- x^2
assign(nameX,x,envir=parent.frame())
}
)
e <- 3
foo2(e,y=5)
cat(e)
______________________________________________ R-devel at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
-- Wolfgang Huber EMBL http://www.embl.de/research/units/genome_biology/huber/contact