CLEANUP: Remove 'digest' as a hard dependency - based on what was just done in 'progressr'

Author: HenrikBengtsson

DESCRIPTION

@@ -1,17 +1,17 @@
 Package: future
-Version: 1.80.0-9001
+Version: 1.80.0-9002
 Title: Unified Parallel and Distributed Processing in R for Everyone
 Depends:
     R (>= 3.2.0)
 Imports:
-    digest,
     globals (>= 0.18.0),
     listenv (>= 0.8.0),
     parallel,
     parallelly (>= 1.44.0),
     tools,
     utils
 Suggests:
+    digest,
     methods,
     RhpcBLASctl,
     R.rsp,
@@ -119,4 +119,4 @@ Collate:
     'utils_api-sessionDetails.R'
     'utils_api-tweak.R'
     'zzz.R'
-Config/roxygen2/version: 8.1.0
+Config/roxygen2/version: 8.1.1

NAMESPACE

@@ -210,7 +210,6 @@ if (getRversion() >= "4.4") export(FUTURE)
 if (getRversion() >= "4.4") export(makeClusterFuture)
 if (getRversion() >= "4.4") importFrom(parallel,recvData)
 if (getRversion() >= "4.4") importFrom(parallel,sendData)
-importFrom(digest,digest)
 importFrom(globals,
   Globals,
   as.Globals,

NEWS.md

@@ -1,5 +1,15 @@
 # Version (development version)
 
+## Significant Changes
+
+ * `digest` is no longer a hard dependency. The package now uses
+   `tools::md5sum(bytes = ...)`, which is available in R (>= 4.5.0), to
+   generate unique IDs for R objects. For older versions of R, it uses
+   `tools::md5sum(files = ...)` via a temporary file, which does not add
+   much overhead because these internal IDs are not generated
+   frequently. For the time being, `digest::digest()` is still used for
+   older versions of R, if **digest** is installed.
+
 # Version 1.80.0 [2026-10-15]
 
 ## Significant Changes

R/utils-uuid.R

@@ -1,14 +1,36 @@
 ## Create a universally unique identifier (UUID) for an R object
 #' @importFrom tools md5sum
-#' @importFrom digest digest
 uuid <- local({
-  ## Use tools::md5sum(), if R (>= 4.5.0). Fall back to digest::digest().
-  if ("bytes" %in% names(formals(md5sum))) {
-    md5 <- function(x) md5sum(bytes = serialize(x, connection = NULL))
-  } else {
-    md5 <- function(x) digest(x, algo = "md5", serialize = TRUE, skip = 0L)
+  ## We need to trick 'R CMD check' that 'md5' is a function already,
+  ## because with md5 <- NULL, 'codetools' triggers a check NOTE.
+  md5 <- function(x) {
+    ## 1. Use the native tools::md5sum(bytes = ...), if R (>= 4.5.0).
+    if ("bytes" %in% names(formals(md5sum))) {
+      impl <- function(x) md5sum(bytes = serialize(x, connection = NULL))
+    } else if (requireNamespace("digest", quietly = TRUE)) {
+      ## 2. On R (< 4.5.0), use digest::digest(), if the 'digest' package
+      ##    is available.
+      impl <- function(x) {
+        digest::digest(x, algo = "md5", serialize = TRUE, skip = 0L)
+      }
+    } else {
+      ## 3. On R (< 4.5.0), fall back to tools::md5sum(files = ...)
+      impl <- function(x) {
+        bytes <- serialize(x, connection = NULL)
+        tmp <- tempfile()
+        on.exit(unlink(tmp))
+        writeBin(bytes, tmp)
+        unname(md5sum(tmp))
+      }
+    }
+
+    ## Memoize md5() function, which will replace it for future calls
+    md5 <<- impl
+
+    ## But for this first call, we need to call it
+    impl(x)
   }
-  
+
   function(source, keep_source = FALSE) {
     uuid <- md5(source)
     if (keep_source) attr(uuid, "source") <- source