[R] basic proto question

[baptiste auguie]

Dear list,

I made the following example of a proto object that contains some data
and a spline interpolation. I don't understand why test$predict()
fails with this error message:

Error: evaluation nested too deeply: infinite recursion / options(expressions=)?

Best regards,

baptiste

test <- proto(source = data.frame(x=1:10, y=rnorm(10)),
              raw = function(.){
                data.frame(xx=.$source$x, yy=.$source$y)
              },
              spline = function(.){
                with(.$raw(), smooth.spline(xx, yy))
                  },
              predict = function(., range=NULL, n=100){
                if(is.null(range))
                  range <- range(.$raw()$xx)

                x.fine <- seq(from=range[1], to=range[2], length=n)

                predict(.$spline(), x.fine)

              }
              )

test$source
test$raw()
test$spline() # OK so far
test$predict() # fails

sessionInfo()
R version 2.10.1 RC (2009-12-06 r50690)
i386-apple-darwin9.8.0

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/C/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] grid      tools     stats     graphics  grDevices utils     datasets
[8] methods   base

other attached packages:
[1] lattice_0.17-26 ggplot2_0.8.5   digest_0.4.1    reshape_0.8.3
[5] plyr_0.1.9      proto_0.3-8     constants_1.0   gtools_2.6.1