On Thu, May 22, 2014 at 10:47 AM, Simon Urbanek <simon.urba...@r-project.org > wrote:
> On May 22, 2014, at 11:33 AM, Tim Keitt <tke...@utexas.edu> wrote: > > > On Thu, May 22, 2014 at 9:19 AM, Simon Urbanek < > simon.urba...@r-project.org> wrote: > > Tim, > > > > On May 21, 2014, at 9:54 PM, Tim Keitt <tke...@utexas.edu> wrote: > > > > > When dealing with object holding pointers that are only valid during a > single session, it would be convenient to exclude them from being saved > with the session image. (I am assuming that `quit` calls `save.image` > before quitting or is it internal?) Currently they are saved with the > pointer converted to NULL. Its a bit surprising for users not realizing the > object is no longer valid. > > > > > > > than's not surprising - it's actually very useful, because it tells you > that the object has been restored. Typically, packages using external > pointers use this to re-inilitialize the object from serialized data or > other sources if possible. > > > > Automatically or with user intervention? > > > Automatically - that is the point :). > Have an example? Do you save a promise? > > > > > My thought is to designate a class name (perhaps "no.save") and > exclude anything that inherits from that. > > > > Why would you want to not save it? It exists, so saving it makes it > possible to decide on the behavior as needed - as opposed to not saving it > and thus losing the information. > > > > That's a valid argument. I don't necessarily disagree, but it does > depend on the situation and the author's intentions. > > > > My question was not about enforcing policy on authors, rather it was > about whether this would add value for those that would like to use it for > cases where they deem it a benefit. I see those as separate issues. > > > > Incidentally, I suggested many years ago hooks in load to make > reinitialization possible. Is there some infrastructure for that in R? (And > actually hooks on save would be quite useful as well eg one could > substitute an object designed to reinitialize the original object on load.) > > > > Load time is typically not an issue, since you can just do it lazily. > (Incidentally, doing that eagerly at load time is the hard part since you'd > have to load the packages necessary in the right order which is not always > possible to determine from the serialization alone. It's a full can of > worms, because R doesn't know anything about sharing and dependencies on > the native side etc.). > > However, having a proper save hook for ext ptrs would be very useful. When > I was asking for it few years ago, Luke mentioned there were issues - maybe > it's something that could be re-visited. > I'd be interested. I can see it might be tricky deciding when to call the hook. THK > > Cheers, > Simon > > > > > Cheers, > > THK > > > > > > Cheers, > > Simon > > > > > > > > > I've hacked a quick implementation below. > > > I did not issue a warning, but it would be a simple fix. > > > > > > Does anyone else see this as useful? > > > > > > THK > > > > > > -- > > > http://www.keittlab.org/ > > > > > > .new.save.image = function (file = ".RData", version = NULL, ascii = > FALSE, > > > compress = !ascii, > > > safe = TRUE, omit.no.save = TRUE) # added > > > "omit.no.save" argument > > > { > > > if (!is.character(file) || file == "") > > > stop("'file' must be non-empty string") > > > opts <- getOption("save.image.defaults") > > > if (is.null(opts)) > > > opts <- getOption("save.defaults") > > > if (missing(safe) && !is.null(opts$safe)) > > > safe <- opts$safe > > > if (missing(ascii) && !is.null(opts$ascii)) > > > ascii <- opts$ascii > > > if (missing(compress) && !is.null(opts$compress)) > > > compress <- opts$compress > > > if (missing(version)) > > > version <- opts$version > > > if (safe) { > > > outfile <- paste0(file, "Tmp") > > > i <- 0 > > > while (file.exists(outfile)) { > > > i <- i + 1 > > > outfile <- paste0(file, "Tmp", i) > > > } > > > } > > > else outfile <- file > > > on.exit(file.remove(outfile)) > > > > > > ### Omit objects inheriting from "no.save" ### > > > > > > objns <- ls(envir = .GlobalEnv, all.names = TRUE) > > > > > > if ( omit.no.save ) ### make part of options? > > > objns <- subset(objns, sapply(objns, function(x) > > > { > > > ! inherits(get(x, envir = .GlobalEnv), "no.save") > > > })) > > > > > > save(list = objns, file = outfile, > > > version = version, ascii = ascii, compress = compress, > > > envir = .GlobalEnv, precheck = FALSE) > > > > > > ### End code changes ### > > > > > > if (safe) > > > if (!file.rename(outfile, file)) { > > > on.exit() > > > stop(gettextf("image could not be renamed and is left in %s", > > > outfile), domain = NA) > > > } > > > on.exit() > > > } > > > > > > setClass("no.save") > > > setClass("test.class", slots = c(s1 = "externalptr")) > > > setIs("test.class", "no.save") > > > reg.obj = "regular object" > > > no.save.obj = new("test.class") > > > .image.file = tempfile() > > > save.image(.image.file) > > > rm(reg.obj, no.save.obj) > > > load(.image.file) > > > print(ls()) > > > unlink(.image.file) > > > .new.save.image(.image.file) > > > rm(reg.obj, no.save.obj) > > > load(.image.file) > > > print(ls()) > > > unlink(.image.file) > > > > > > [[alternative HTML version deleted]] > > > > > > ______________________________________________ > > > R-devel@r-project.org mailing list > > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > > > > > > > > > > -- > > http://www.keittlab.org/ > > -- http://www.keittlab.org/ [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
