Dear R Users,
I have a couple of proto objects like:
wedge <- proto(expr={
start.year <- 2008
end.year <- 2050
})
star.rating <- wedge$proto(
star = c(4, 5, 8, 10),
gain = c(0, .3, .5, .7),
cost = c(0, 2100, 4000, 7500),
star.rating <- function(., year) 6.0,
setup = function(.){
.$cost.for.star <- approxfun(.$star, .$cost)
.$gain.for.star <- approxfun(.$star, .$gain)
},
test = function(., year) {
gs <- .$with(gain.for.star)(.$star.rating(year))
}
)
And a function to create and modify 'instances':
create.star.rating <- function(switch.years, star.ratings) {
res <- star.rating$proto(switch.years = switch.years, star.ratings =
star.ratings)
res$setup()
res
}
When I use them as follows:
ee <- create.star.rating(ratings, switch.years)
ee$test(2009)
The second line gives me the error message:
"Error in .$with(gain.for.star)(.$star.rating(year)) :
object "y" not found"
I understand why this happens (when objects are inserted into a proto
their environment is set to that of the proto)... but I can't figure out
how to get around it!
I have tried setting the environments of the functions created in setup
as follows:
setup = function(.){
t1 <- approxfun(.$star, .$cost)
t2 <- approxfun(.$star, .$gain)
.$cost.for.star <- t1
.$gain.for.star <- t2
environment(.$cost.for.star) <- environment(t1)
environment(.$gain.for.star) <- environment(t2)
}
But then I get the error:
"Error in get("gain.for.star", env = `*tmp*`, inherits = TRUE) :
object "*tmp*" not found"
Which I think occurs because the last two lines in 'setup' only create
references to their respective environments which disappear on exit of
'setup'.
Any ideas?
Regards,
Simon Knapp.
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