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# For our purposes, cache objects must support these methods.
is_cache_object <- function(x) {
# Use tryCatch in case the object does not support `$`.
tryCatch(
is.function(x$get) && is.function(x$set),
error = function(e) FALSE
)
}
# Given a cache object, or string "app" or "session", return appropriate cache
# object.
resolve_cache_object <- function(cache, session) {
if (identical(cache, "app")) {
cache <- getShinyOption("cache", default = NULL)
} else if (identical(cache, "session")) {
cache <- session$cache
}
if (is_cache_object(cache)) {
return(cache)
}
stop('`cache` must either be "app", "session", or a cache object with methods, `$get`, and `$set`.')
}
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