[Rd] Evaluation puzzle

[Gabor Grothendieck]

On Thu, Nov 11, 2010 at 3:08 PM, Terry Therneau <therneau at mayo.edu> wrote:
> The survexp function can fail when called from another function.  The "why" of
> this has me baffled, however.
>
> Here is a simple test case, using a very stripped down version of survexp:
>
> survexp.test <- function(formula, data,
>        weights, subset, na.action, rmap,
>        times,  cohort=TRUE,  conditional=FALSE,
>        ratetable=survexp.us, scale=1, npoints, se.fit,
>        model=FALSE, x=FALSE, y=FALSE) {
>    call <- match.call()
>    m <- match.call(expand.dots=FALSE)
>
>    # keep the first element (the call), and the following selected arguments
>    m <- m[c(1, match(c('formula', 'data', 'weights', 'subset', 'na.action'),
>                      names(m), nomatch=0))]
>    m[[1]] <- as.name("model.frame")
>
>    # Add in the ratetable variables
>    varlist <- attr(ratetable, 'dimid')
>    tform <- paste(deparse(formula), paste(varlist, collapse='+'), sep='+')

At the above statement you have lost the environment of your formula.

>    m$formula <- tform

Replace this with:

m$formula <- as.formula(tform, environment(formula))



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