You could (in addition to the other suggestions) try package proto (. refers
to "self" but see also the package's vignette)
account <- proto(
deposit = function(., amount) {
if(amount <= 0) stop("Deposits must be positive!\n")
.$total <- .$total + amount
cat(amount,"deposited. ")
.$balance()
},
withdraw = function(., amount) {
if(amount > .$total) stop("You don't have that much money!\n")
.$total <- .$total - amount
cat(amount,"withdrawn. ")
.$balance()
},
balance = function(.) {
cat("Your balance is", .$total, "\n\n")
},
new = function(., total) .$proto(total = total)
)
a <- account$new(10)
a$withdraw(10)
a$balance()
On Sun, Mar 20, 2011 at 2:02 AM, Russ Abbott <russ.abb...@gmail.com> wrote:
> Actually, I guess I'm not really talking about objects. I was looking
> through the scoping demo. It uses this function.
>
> > open.account <- function(total) {
>
> +
>
> + list(
>
> + deposit = function(amount) {
>
> + if(amount <= 0)
>
> + stop("Deposits must be positive!\n")
>
> + total <<- total + amount
>
> + cat(amount,"deposited. Your balance is", total, "\n\n")
>
> + },
>
> + withdraw = function(amount) {
>
> + if(amount > total)
>
> + stop("You don't have that much money!\n")
>
> + total <<- total - amount
>
> + cat(amount,"withdrawn. Your balance is", total, "\n\n")
>
> + },
>
> + balance = function() {
>
> + cat("Your balance is", total, "\n\n")
>
> + }
>
> + )
>
> + }
>
>
> I wanted to re-write the function so that instead of referring to *total
> *in
> *deposit *and *withdraw *I could refer to *balance*. Something like this,
>
>
> withdraw = function(amount) {
> + if(amount > total)
> + stop("You don't have that much money!\n")
> + total <<- total - amount
> + cat(amount,"withdrawn. Your balance is", *this,balance()*,
> "\n\n")
>
> But that doesn't work. Is it possible to do this?
>
> Thanks.
>
> *-- Russ Abbott*
> *_____________________________________________*
> *** Professor, Computer Science*
> * California State University, Los Angeles*
>
> * Google voice: 747-*999-5105
> * blog: *http://russabbott.blogspot.com/
> vita: http://sites.google.com/site/russabbott/
> *_____________________________________________*
>
>
>
> On Sat, Mar 19, 2011 at 4:40 PM, Gabor Grothendieck <
> ggrothendi...@gmail.com
> > wrote:
>
> > On Sat, Mar 19, 2011 at 6:34 PM, Russ Abbott <russ.abb...@gmail.com>
> > wrote:
> > > Is it possible to refer to an object from within a method, as in *this
> > *in
> > > Java? I can't find anything about this in the documentation. Sorry if
> I
> > > missed it.
> > >
> >
> > Assuming you are referring to S3, the first argument to a method is
> > the object (unless specified otherwise in the UseMethod call but that
> > is rarely done).
> >
> >
> > --
> > Statistics & Software Consulting
> > GKX Group, GKX Associates Inc.
> > tel: 1-877-GKX-GROUP
> > email: ggrothendieck at gmail.com
> >
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
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> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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