quick and dirty caching of R objects, via a %<--% operator

dirty_caching.R

# quick & dirty caching of R objects - run the expression in b iff an RDS file
# for the object doesn't exist, otherwise load the object
`%<--%` <- function (a, b) {
  name <- deparse(substitute(a))
  file <- paste0(name, ".rds")
  if (file.exists(file)) {
    obj <- readRDS(file)
  } else {
    obj <- b
    saveRDS(obj, file)
  }
  assign(name, obj, envir = parent.frame())
}

flush <- function (object) {
  name <- deparse(substitute(object))
  file <- paste0(name, ".rds")
  suppressWarnings(result <- file.remove(file))
  invisible(result)
}

# # example:
# foo <- function() {Sys.sleep(3); 1}
# system.time(test %<--% foo() * 2)  # slow
# system.time(test %<--% foo() * 2)  # fast
# flush(test)
# system.time(test %<--% foo() * 2)  # slow
# flush(test)