import rlang and later

Author: shikokuchuo

DESCRIPTION

@@ -21,9 +21,10 @@ SystemRequirements: 'libfswatch', or 'cmake' to compile from package sources
 Depends: 
     R (>= 3.6)
 Imports:
-    R6
-Suggests: 
     later,
+    R6,
+    rlang
+Suggests: 
     testthat (>= 3.0.0)
 RoxygenNote: 7.3.2
 Roxygen: list(markdown = TRUE)

NAMESPACE

@@ -2,4 +2,5 @@
 
 export(watcher)
 importFrom(R6,R6Class)
+importFrom(later,run_now)
 useDynLib(watcher, .registration = TRUE)

R/watch.R

@@ -4,15 +4,17 @@
 #' background.
 #'
 #' A limited subset of filesystem events are watched, namely: Created, Updated,
-#' Removed and Renamed. Default latency is 1s.
+#' Removed and Renamed. Events are 'bubbled' such that if a single event
+#' triggers multiple event flag types, the callback will be called only once.
+#' Default latency is 1s.
 #'
 #' @param path character path to a file or directory to watch. Defaults to the
 #'   current working directory.
 #' @param recursive logical value, default TRUE, whether to recursively scan
 #'   `path`, including all subdirectories.
 #' @param callback (optional) a function (taking no arguments) to be called each
-#'   time an event is triggered - requires the \pkg{later} package. The default,
-#'   `NULL`, causes event paths and types to be written to `stdout` instead.
+#'   time an event is triggered. The default, `NULL`, causes event flag types
+#'   and paths to be written to `stdout` instead.
 #'
 #' @return A 'Watcher' R6 class object. Start and stop background monitoring
 #'   using the `$start()` and `$stop()` methods - these return a logical value
@@ -35,15 +37,16 @@ Watcher <- R6Class(
   "Watcher",
   public = list(
     active = FALSE,
-    callback = NULL,
     path = NULL,
     recursive = NULL,
     initialize = function(path = getwd(), recursive = TRUE, callback = NULL) {
       if (is.null(self$path)) {
         self$path <- path.expand(path)
         self$recursive <- as.logical(recursive)
-        self$callback <- callback
-        private$watch <- .Call(watcher_create, self$path, self$recursive, self$callback)
+        if (!is.null(callback) && !is.function(callback)) {
+          callback <- rlang::as_function(callback)
+        }
+        private$watch <- .Call(watcher_create, self$path, self$recursive, callback)
       }
       invisible(self)
     },

R/watcher-package.R

@@ -1,4 +1,11 @@
+#' @importFrom later run_now
 #' @importFrom R6 R6Class
 #' @useDynLib watcher, .registration = TRUE
 #' @keywords internal
 "_PACKAGE"
+
+# for R CMD check note: All declared Imports should be used.
+# rlang is not loaded unless used, later is loaded but used only at C level
+.internal <- function() {
+  if (FALSE) rlang::as_function(identity)(later::run_now())
+}

README.md

@@ -51,9 +51,8 @@ w
 #> <Watcher>
 #>   Public:
 #>     active: FALSE
-#>     callback: function () 
-#>     initialize: function (path = getwd(), recursive = TRUE, callback = NULL) 
-#>     path: /tmp/Rtmp8wU9e9/watcher-example
+#>     initialize: function (path, recursive, callback, latency) 
+#>     path: /tmp/RtmpvAax6s/watcher-example
 #>     recursive: TRUE
 #>     start: function () 
 #>     stop: function () 

man/watcher.Rd

@@ -1,5 +1,7 @@
 #include "watcher.h"
 
+void (*eln2)(void (*)(void *), void *, double, int);
+
 static const R_CallMethodDef callMethods[] = {
   {"watcher_create", (DL_FUNC) &watcher_create, 3},
   {"watcher_start_monitor", (DL_FUNC) &watcher_start_monitor, 1},
@@ -9,6 +11,7 @@ static const R_CallMethodDef callMethods[] = {
 
 void attribute_visible R_init_watcher(DllInfo* dll) {
   if (fsw_init_library() != FSW_OK) return;
+  eln2 = (void (*)(void (*)(void *), void *, double, int)) R_GetCCallable("later", "execLaterNative2");
   R_registerRoutines(dll, NULL, callMethods, NULL, NULL);
   R_useDynamicSymbols(dll, FALSE);
   R_forceSymbols(dll, TRUE);

src/init.c

@@ -20,15 +20,6 @@ static void session_finalizer(SEXP xptr) {
   fsw_destroy_session(handle);
 }
 
-void (*eln2)(void (*)(void *), void *, double, int) = NULL;
-
-static void load_later_safe(void *data) {
-  SEXP call, fn = (SEXP) data;
-  PROTECT(call = Rf_lang2(fn, Rf_mkString("later")));
-  Rf_eval(call, R_GlobalEnv);
-  UNPROTECT(1);
-}
-
 static void exec_later(void *data) {
   SEXP call, fn = (SEXP) data;
   PROTECT(call = Rf_lcons(fn, R_NilValue));
@@ -50,7 +41,7 @@ static void get_event_flag_name(const int flag, char *buf) {
 }
 
 static void process_events(fsw_cevent const *const events, const unsigned int event_num, void *data) {
-  if (data != R_NilValue && eln2 != NULL) {
+  if (data != R_NilValue) {
     eln2(exec_later, data, 0, 0);
   } else {
     char buf[8]; // large enough for subset of events handled by get_event_flag_name()
@@ -76,11 +67,6 @@ SEXP watcher_create(SEXP path, SEXP recursive, SEXP callback) {
 
   const char *watch_path = CHAR(STRING_ELT(path, 0));
   const int recurse = LOGICAL(recursive)[0];
-  if (callback != R_NilValue) {
-    SEXPTYPE typ = TYPEOF(callback);
-    if (typ != CLOSXP && typ != BUILTINSXP && typ != SPECIALSXP)
-      Rf_error("'callback' must be a function");
-  }
 
   FSW_HANDLE handle = fsw_init_session(system_default_monitor_type);
   if (handle == NULL) {
@@ -121,15 +107,11 @@ SEXP watcher_create(SEXP path, SEXP recursive, SEXP callback) {
 SEXP watcher_start_monitor(SEXP session) {
 
   FSW_HANDLE handle = (FSW_HANDLE) R_ExternalPtrAddr(session);
+
   pthread_t thr;
   pthread_attr_t attr;
-
   pthread_attr_init(&attr);
   pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
-
-  if (eln2 == NULL && R_ToplevelExec(load_later_safe, (void *) Rf_install("loadNamespace"))) {
-    eln2 = (void (*)(void (*)(void *), void *, double, int)) R_GetCCallable("later", "execLaterNative2");
-  }
   const int ret = pthread_create(&thr, &attr, &watcher_thread, handle);
   pthread_attr_destroy(&attr);
 

src/watcher.c

@@ -57,8 +57,4 @@ test_that("watcher() callbacks", {
   rm(w)
 })
 
-test_that("watcher() validation", {
-  expect_error(watcher(callback = "callback"), "must be a function")
-})
-
 unlink(dir, recursive = TRUE, force = TRUE)