Good suggestion for this case.
But the general problem is tricky. What about reference objects
contained in attributes or slots of other objects, etc? What is needed
for total copying is a switch in the low-level duplication code that
says to copy reference objects. It's also possible that one does NOT
want all such objects copied.
For now, it may be that specialized copy() methods are needed for
classes that have subsidiary reference objects inside non-reference objects.
John
On 5/11/11 6:37 AM, Hadley Wickham wrote:
Hi Manuel,
The source code for copy is short and pretty readable, so I'd
encourage you to look at it:
setRefClass("XXX")$copy
Class method definition for method copy()
function (shallow = FALSE)
{
def<- .refClassDef
value<- new(def)
vEnv<- as.environment(value)
selfEnv<- as.environment(.self)
for (field in names(def@fieldClasses)) {
if (shallow)
assign(field, get(field, envir = selfEnv), envir = vEnv)
else {
current<- get(field, envir = selfEnv)
if (is(current, "envRefClass"))
current<- current$copy(FALSE)
assign(field, current, envir = vEnv)
}
}
value
}
The basic problem is that you have a list of reference class objects,
and currently copy does not recurse into lists. I think this could be
fixed with
deep_copy<- function(x) {
if (is(current, "envRefClass")) {
x$copy()
} else if (is.list(x))
lapply(x, deep_copy)
} else {
x
}
}
function (shallow = FALSE){
def<- .refClassDef
value<- new(def)
vEnv<- as.environment(value)
selfEnv<- as.environment(.self)
for (field in names(def@fieldClasses)) {
if (shallow)
assign(field, get(field, envir = selfEnv), envir = vEnv)
else {
current<- get(field, envir = selfEnv)
assign(field, deep_copy(current), envir = vEnv)
}
}
value
}
Hadley
2011/5/11 Manuel Castejón Limas<manuel.caste...@unileon.es>:
Dear Hadley,
Thank you very much for your interest in the question proposed.
The Con class is a Reference Class. P and k are from class listCon.
I provide in the following lines a little more detail in order to be able
to reproduce the case.
#Class declaration
gCon<- setRefClass("Con", fields=list(from="ANY",weight="numeric"))
gListAMORE<- setRefClass("listAMORE", fields=list(.Data="list"))
gListCon<- setRefClass("listCon", contains="listAMORE")
# Let's create a few connections
con1<- gCon$new(from=1, weight=1.1)
con2<- gCon$new(from=2, weight=2.2)
con3<- gCon$new(from=3, weight=3.3)
# And a list of connections
lcon<-gListCon$new()
lcon$.Data<- list(con1, con2, con3)
# At this point, lcon contains:
lcon$.Data
[[1]]
An object of class "Con"
<environment: 0x9a1534>
[[2]]
An object of class "Con"
<environment: 0xcd7ff0>
[[3]]
An object of class "Con"
<environment: 0xdca724>
# Let's copy lcon to k
k<- lcon$copy(shallow=FALSE)
# Now k is a new object but the cons are shared with lcon!
k$.Data
[[1]]
An object of class "Con"
<environment: 0x9a1534>
[[2]]
An object of class "Con"
<environment: 0xcd7ff0>
[[3]]
An object of class "Con"
<environment: 0xdca724>
Best regards
Manuel
El 11/05/11 14:00, "Hadley Wickham"<had...@rice.edu> escribió:
2011/5/10 Manuel Castejón Limas<manuel.caste...@unileon.es>:
Dear all,
I've just discovered the 'Reference Classes'.
In a previous attempt ---a year ago--- to re-implement in a Object
Oriented
fashion the AMORE package using S4 classes I strongly felt the need of
such
capability. It's great to have the Reference Classes now available.
Along
with the discovery of the Rcpp package, this new programming paradigm
has
boosted my interest in rewriting that package.
Nevertheless, I have found a surprising behavior in the
$copy(shallow=FALSE)
method. Let's have a look at the results which I believe are
self-explanatories. The ".Data" field is a list which contains objects
from
the "Con" class ---connections for what is worth---.
What sort of class is the Con class? S4 or reference?
Hadley
--
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
