Ross Boylan wrote:
I defined an S4 class with a slot i. Then I wrote a regular function
that attempted to increment i.
[... details deleted ...]
What do I need to do to update slot values?
Here are some possibly relevant code fragments
setClass("CompletePathMaker",
representation(i="integer",
timeOffset="numeric", # to avoid 0's
truePaths="TruePaths")
)
nextPath <- function(pm){ #pm is a CompletePathMaker
[EMAIL PROTECTED] <- [EMAIL PROTECTED](1)
[etc]
I'm trying to make the class behave like an iterator, with i keeping
track of its location. I'm sure there are more R'ish ways to go, but
I'm also pretty sure I'm going to want to be able to update slots.
Hello Ross,
I see that your question was related to S4, but I just noticed a
solution based on the R.oo package so I thought I would add a solution
based on the proto package too. We had similar problems several times
ago and (to my surprise) found R to be an extremely flexible language
even for these things. Our favorite solution is available as
package(proto). It requires R 2.1, because of several subtle
improvements regarding environments, which made our implementation more
streamlined.
Does the following example do what you intended?
##=====================================================
library(proto)
## 1) define an object
CompletePathMaker <- proto(
index = 0,
bumpIndex = function(., dindex = 1)
.$index <- .$index + as.integer(dindex)
)
## 2) create a child object of CompletePathMaker
cpm <- CompletePathMaker$proto()
## 3) set the index component to 3
cpm$index <- 3
## 4) iterate the index
cpm$bumpIndex(2)
## print the result
cpm$index
##=====================================================
This approach is very compact and needs only one new function: proto.
Also note how simple it is conceptually. We did not even create any
classes. We just created a parent object CompletePathMaker and a child
to it, cpm, and got everything else via delegation (i.e. inheritance).
Hope it helps
Thomas P.
______________________________________________
R-help@stat.math.ethz.ch mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
