Options that are local to the package that sets them
On Fri, Oct 31, 2014 at 8:16 PM, William Dunlap <wdunlap at tibco.com> wrote:
You can put the following 3 objects, an environment and 2 functions
that access it, in any package that need some package-specific
storage (say your pkgB1 and pkgB2).
.pkgLocalStorage <- new.env(parent = emptyenv())
assignInPkgLocalStorage <- function(name, object) {
.pkgLocalStorage[[name]] <- object
}
getFromPkgLocalStorage <- function(name, object) {
.pkgLocalStorage[[name]]
}
Leave the environment private and export the functions. Then a user can
use them as
pkgB1::assignInPkgLocalStorage("myPallete", makeAPallete(1,2,3))
pkgB2::assignInPkgLocalStorage("myPallete", makeAPallete(5,6,7))
pkgB1::getFromPkgLocalStorage("myPallete") # get the 1,2,3 pallete
I am trying to avoid requiring pkgBn to do this kind of magic. I just want it to call function(s) from pkgA. But maybe something like this would work. In pkgBn: my_palettes <- pkgA::palette_factory() and my_palettes is a function or an environment that has the API functions to modify my_palettes itself (via closure if it is a function), e.g. my_palettes$add_palette(...) my_palettes$get_palette(...) or if it is a function, then my_palettes(add(...), ...) my_palettes(get(...), ...) etc. This would work, right? I'll try it in a minute. Gabor
If only one of pkgB1 and pkgB2 is loaded you can leave off the pkgBn::. A package writer can always leave off the pkgBn:: as well. Bill Dunlap TIBCO Software wdunlap tibco.com On Fri, Oct 31, 2014 at 4:34 PM, G?bor Cs?rdi <csardi.gabor at gmail.com> wrote:
Dear All, I am trying to do the following, and could use some hints. Suppose I have a package called pkgA. pkgA exposes an API that includes setting some options, e.g. pkgA works with color palettes, and the user of the package can define new palettes. pkgA provides an API to manipulate these palettes, including defining them. pkgA is intended to be used in other packages, e.g. in pkgB1 and pkgB2. Now suppose pkgB1 and pkgB2 both set new palettes using pkgA. They might set palettes with the same name, of course, they do not know about each other. My question is, is there a straightforward way to implement pkgA's API, such that pkgB1 and pkgB2 do not interfere? In other words, if pkgB1 and pkgB2 both define a palette 'foo', but they define it differently, each should see her own version of it. I guess this requires that I put something (a function?) in both pkgB1's and pkgB2's package namespace. As I see it, this can only happen when pkgA's API is called from pkgB1 (and pkgB2). So at this time I could just walk up the call tree and put the palette definition in the first environment that is not pkgA's. This looks somewhat messy, and I am probably missing some caveats. Is there a better way? I have a feeling that this is already supported somehow, I just can't find out how. Thanks, Best Regards, Gabor
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