On Tue, Mar 31, 2009 at 12:41 PM, Martin Morgan <[email protected]> wrote:
> I don't konw about preferred, but one method is
>
> pkgVars <- local({
> x <- NULL
> list(getX=function() x, setX=function(value) x <<- value)
> })
>
> with use
>
> > pkgVars$getX()
> ...
> This introduces a different programming paradigm (a list of functions)
> that might not be familiar for end-users and is not readily amenable
> to documentation.
Why "not readily amenable to documentation"? If the user doesn't need to
understand the structure, he can consider the "$" as simply part of the
function name. And I wouldn't name it pkgVars but pkg.
> A probably better way is
>
> pkgVars <- new.env(parent=emptyenv())
> getX <- function() get("x", pkgVars, inherits=FALSE)
> setX <- function(value) assign("x", value, envir=pkgVars)
>
I think a simpler, clearer way to make getX etc. globally visible is:
local({
x <- NULL
getX <<- function() x
setX <<- function(value) x <<- value
})
To my taste, this is much cleaner than explicitly referencing environments.
-s
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