I have constructed the following functions and need a little clarification:
### function to fit the model parameters
jml.fit <- function(dat, con = 1e-3, bias=FALSE, ...){
do stuff ...
}
### default function which calls jml.fit
jml.default <- function(dat, con = 1e-3, bias=FALSE, ...){
result <- jml.fit(dat, con = 1e-3, bias)
result$call <- match.call()
class(result) <- "jml"
result
}
### Function to make use of formula
jml.formula <- function(formula, data, na.action, subset, ...){
mf <- match.call(expand.dots = FALSE)
m <- match(c("formula", "data", "na.action", "subset"), names(mf), 0L)
mf <- mf[c(1L, m)]
mf$drop.unused.levels <- TRUE
mf[[1L]] <- as.name("model.frame")
mf <- eval(mf, parent.frame())
mt <- attr(mf, "terms")
dat <- mf
result <- jml.default(dat, ...)
result$call <- match.call()
result$formula <- formula
result
}
### and the generic function
jml <- function(dat, con = 1e-3, bias=FALSE, ...) UseMethod("jml")
Writing R Extensions states, "If the generic specifies defaults, all methods
should use the same defaults."
In my example above, the generic function has 2 defaults: one for argument con
and another bias. I'm a little confused on exactly how the generic function
should be structured for proper package development.
I think the options are:
1) jml <- function(dat, con = 1e-3, bias=FALSE, ...) UseMethod("jml")
2) jml <- function(x, con = 1e-3, bias=FALSE, ...) UseMethod("jml")
3) jml <- function(formula, data, na.action, subset, con = 1e-3, bias = FALSE,
...) UseMethod("jml")
I'm inclined to believe #3 is correct because the .Rd page needs to reflect the
args in this function, is that right? Then, this generic function would include
the formula, data, na.action, and subset and it includes the proper defaults as
the other functions.
Thank you
Harold
> sessionInfo()
R version 2.10.0 (2009-10-26)
i386-pc-mingw32
locale:
[1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C
[5] LC_TIME=English_United States.1252
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] scoreFoo_1.1 MiscPsycho_1.4 statmod_1.4.1
loaded via a namespace (and not attached):
[1] tools_2.10.0
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