wrapper <-function(WhichApproach=1, splineDF=4 ){
#	Create toy dataset
nID<-25
IDnames<-LETTERS[1:nID]

longdat<-data.frame( x=rep(-10:10, nID) / 3 , ID= rep( IDnames , each=21)
)
set.seed(5)
longdat$x<-longdat$x + rnorm(nrow(longdat))/10
IDeffect<-rnorm(nID) * 20
names(IDeffect) <- IDnames
longdat$IDeffect<-IDeffect[as.character(longdat$ID)]
longdat$y<- (longdat$x 
			+ longdat$x^3
			+ (longdat$x-1)^4  / 5
			+ 1/(abs(longdat$x/50) + 0.02)
			+ longdat$IDeffect
			+ rnorm(1:nrow(longdat)) * 2
			)
longdat<-longdat[order(longdat$x),]

library(splines)
#	Calling ns within lm works fine:
mylm<- lm( y ~ ns(x,df=splineDF), data=longdat)
longdat$lmfit<-predict(mylm)
library(ggplot2)
print(
	ggplot(longdat, aes(x, y)) 
	+ geom_point(shape=1)
	+ geom_line(aes(x=x, y=lmfit), color="red")
)


cat("Enter to attempt lme.")
readline()
library(nlme)

if(WhichApproach==1) {
# returns: "Error in eval(expr, envir, enclos) : object 'splineDF' not found"
#
# First make sure splineDF does not exist in .GlobalEnv, else we would be in WhichApproach==2.
if(exists("splineDF", where=".GlobalEnv")) remove(list="splineDF", pos=".GlobalEnv")
mylme<-lme(fixed= y ~ ns(x, df=splineDF)
			, random= ~ 1 | ID
			, correlation = corAR1()
			, data=longdat
		)
} else if(WhichApproach==2) {
# returns: "Error in model.frame.default(formula = ~ID + y + x + splineDF, data = list( : 
# variable lengths differ (found for 'splineDF')"
assign(x="splineDF", value=splineDF, pos=".GlobalEnv")
mylme<-lme(fixed= y ~ ns(x, df=splineDF)
			, random= ~ 1 | ID
			, correlation = corAR1()
			, data=longdat
		)
} else if (WhichApproach==3) {

thecommandstring<- paste("mylme<-lme(fixed= y ~ ns(x, df=", splineDF, ") , random= ~ 1 | ID , correlation = corAR1() , data=longdat)")
thecommandstring
eval(parse(text=thecommandstring))

} else {
	stop(paste("WhichApproach=", WhichApproach, " not valid."))
}

mylme
longdat$fullfit<-predict(mylme) 

library(ggplot2)
print(
	ggplot( longdat, aes(x,y)) 
	+ geom_point(shape=1)
	+ facet_wrap( ~ ID )
	+ geom_line( aes(x, fullfit), color="red")
)

invisible(mylme)
}