best practice(s) for retrieving a local variable from a closure
On Sat, Apr 9, 2011 at 3:27 PM, Barry Rowlingson
<b.rowlingson at lancaster.ac.uk> wrote:
On Sat, Apr 9, 2011 at 6:29 PM, Benjamin Tyner <btyner at gmail.com> wrote:
The above feels a bit like snooping where I wasn't invited.
You could do something like
?mq <- function(a) {
? ? force(a)
? ? list(getA = function()a,
? ? ? ? ?setA = function(newA) a <<- newA,
? ? ? ? ?fun = function(x)x^a
? ? )
?}
to make it clear that you expect people to look at or change
fun's 'a'.
?Once you start doing a lot of that though you may as well go the whole OO hog and use the proto or R.oo packages... Barry
In the case of proto it would be this: library(proto) mq <- proto(fun = function(., x) x^.$a) mq$a <- 2 mq$a # 2 mq$fun(3) # 9 or you could make explicit getter and setter functions though, as seen, they are not really needed: mq <- proto(fun = function(., x) x^.$a, getA = function(.) .$a, setA = function(., a) .$a <- a) mq$setA(3) mq$getA() # 3 mq$fun(4) # 64
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