Hi Eric,
Thank you for your answer!
On Mon, 27 Aug 2018 21:48:50 +0300
Eric Berger <ericjber...@gmail.com> wrote:
> you might want to consider the more recent R6 package
Indeed, R6 has private fields which fits my idea of an object with
mutable state even better.
My original problem seems to be solved and I'm posting my code (CC0) in
case someone else needs it as a reference:
require(digest); require(R6)
memoised <- R6Class(
"memoised", lock_objects=T, lock_class=T, cloneable=F,
private=list(fun=NULL, storage=NULL, cache=NULL),
public=list(
initialize=function(fun, storage) { # constructor
private$fun <- fun
private$storage <- storage
private$cache <- tryCatch(
{
load(storage)
cache
}, error = function(e) {
new.env(T, emptyenv())
}
)
},
eval=function(...) { # behave as cached fun
hash <- digest(list(...), algo="sha1")
if (exists(hash, private$cache)) return(get(hash,
private$cache))
val <- private$fun(...)
assign(hash, val, private$cache)
val
},
par.eval=function(args, cl) { # args is list of argument lists
# hash all because we'll need them later
hashes <- lapply(args, digest, algo="sha1")
# indices of not yet evaluated in the original args
array
missing <- Filter(function(i) !exists(hashes[[i]],
private$cache), seq_along(args))
# evaluate and save them
values <- parLapply(cl, args[missing], function(l)
do.call(private$fun,l))
private$cache[hashes[missing]] <- values
# get all requested hashes
private$cache[hashes]
},
finalize=function() { # destructor
cache <- private$cache # must have known name for
restore
save(cache, file=private$storage)
}
)
)
It's still a mystery why did setRefClass refuse to lock my class, but
at least it's not blocking my progress.
--
Best regards,
Ivan
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