use R6 class

Author: shikokuchuo

DESCRIPTION

@@ -11,16 +11,18 @@ Authors@R:
       person(given = "Posit Software, PBC",
              role = "cph"))
 Description: R binding for 'libfswatch', a filesystem monitoring library. All
-    functions are asynchronous and do not block your session. Set watches on
-    files or directories recursively. Filter by type of event. Log activity, or
-    trigger an R function to run when a specified event occurs. 
+    functions are asynchronous and do not block the session. Set watches on
+    files or directories recursively. Log activity, or trigger an R function to
+    run when an event occurs. 
 License: MIT + file LICENSE
 BugReports: https://github.com/shikokuchuo/watcher/issues
 URL: https://shikokuchuo.net/watcher/, https://github.com/shikokuchuo/watcher/
 Encoding: UTF-8
 SystemRequirements: 'libfswatch', or 'cmake' to compile from package sources
 Depends: 
     R (>= 3.6)
+Imports:
+    R6
 Suggests: 
     later,
     testthat (>= 3.0.0)

NAMESPACE

@@ -1,7 +1,5 @@
 # Generated by roxygen2: do not edit by hand
 
-S3method(print,watch)
 export(watcher)
-export(watcher_start)
-export(watcher_stop)
+importFrom(R6,R6Class)
 useDynLib(watcher, .registration = TRUE)

R/watch.R

@@ -13,45 +13,51 @@
 #' @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.
-#' @param watch a 'watch' object.
 #'
-#' @return For [watcher]: a 'watch' object. \cr
-#'   For [watcher_start] and [watcher_stop]: invisibly, `TRUE` upon success or
-#'   `FALSE` otherwise.
+#' @return A 'Watcher' R6 class object.
 #'
 #' @examples
-#' watch <- watcher(tempdir())
-#' isTRUE(watcher_start(watch))
-#' watch
-#' isTRUE(watcher_stop(watch))
-#' watch
+#' w <- watcher(tempdir())
+#' isTRUE(w$start())
+#' w
+#' isTRUE(w$stop())
+#' w
 #'
 #' @export
 #'
 watcher <- function(path = getwd(), recursive = TRUE, callback = NULL) {
-  .Call(watcher_create, path, recursive, callback)
+  Watcher$new(path, recursive, callback)
 }
 
-#' @rdname watcher
-#' @export
-#'
-watcher_start <- function(watch) {
-  invisible(.Call(watcher_start_monitor, watch))
-}
-
-#' @rdname watcher
-#' @export
-#'
-watcher_stop <- function(watch) {
-  invisible(.Call(watcher_stop_monitor, watch))
-}
-
-#' @export
-#'
-print.watch <- function(x, ...) {
-
-  cat(sprintf("< watch >\n  path: %s\n  recursive: %s\n  active: %s\n",
-              attr(x, "path"), attr(x, "recursive"), attr(x, "active")))
-  invisible(x)
-
-}
+Watcher <- R6Class(
+  "Watcher",
+  public = list(
+    active = FALSE,
+    callback = NULL,
+    path = NULL,
+    recursive = TRUE,
+    initialize = function(path = getwd(), recursive = TRUE, callback = NULL) {
+      self$path <- path.expand(path)
+      self$recursive <- as.logical(recursive)
+      self$callback <- callback
+      private$watch <- .Call(watcher_create, self$path, self$recursive, self$callback)
+    },
+    start = function() {
+      res <- .Call(watcher_start_monitor, private$watch)
+      if (res) self$active <- TRUE
+      invisible(res)
+    },
+    stop = function() {
+      res <- invisible(.Call(watcher_stop_monitor, private$watch))
+      if (res) self$active <- FALSE
+      invisible(res)
+    },
+    print = function(...) {
+      cat(sprintf("<Watcher>\n  start()\n  stop()\n  path: %s\n  recursive: %s\n  active: %s\n",
+                  self$path, self$recursive, self$active))
+    }
+  ),
+  private = list(
+    watch = NULL
+  )
+)

R/watcher-package.R

@@ -1,3 +1,4 @@
+#' @importFrom R6 R6Class
 #' @useDynLib watcher, .registration = TRUE
 #' @keywords internal
 "_PACKAGE"

README.Rmd

@@ -51,16 +51,19 @@ dir <- file.path(tempdir(), "watcher-example")
 dir.create(dir)
 
 w <- watcher(dir, recursive = TRUE, callback = function() print("event triggered"))
+w
+w$start()
 
-watcher_start(w)
 Sys.sleep(1L)
 file.create(file.path(dir, "oldfile"))
 later::run_now(2L)
+
 file.rename(file.path(dir, "oldfile"), file.path(dir, "newfile"))
 later::run_now(2L)
+
 file.remove(file.path(dir, "newfile"))
 later::run_now(2L)
-watcher_stop(w)
 
+w$stop()
 unlink(dir, force = TRUE)
 ```

README.md

@@ -45,22 +45,31 @@ dir <- file.path(tempdir(), "watcher-example")
 dir.create(dir)
 
 w <- watcher(dir, recursive = TRUE, callback = function() print("event triggered"))
+w
+#> <Watcher>
+#>   start()
+#>   stop()
+#>   path: /tmp/RtmpTjz7M7/watcher-example
+#>   recursive: TRUE
+#>   active: FALSE
+w$start()
 
-watcher_start(w)
 Sys.sleep(1L)
 file.create(file.path(dir, "oldfile"))
 #> [1] TRUE
 later::run_now(2L)
 #> [1] "event triggered"
+
 file.rename(file.path(dir, "oldfile"), file.path(dir, "newfile"))
 #> [1] TRUE
 later::run_now(2L)
 #> [1] "event triggered"
+
 file.remove(file.path(dir, "newfile"))
 #> [1] TRUE
 later::run_now(2L)
 #> [1] "event triggered"
-watcher_stop(w)
 
+w$stop()
 unlink(dir, force = TRUE)
 ```

man/watcher-package.Rd

@@ -59,7 +59,7 @@ void* watcher_thread(void *args) {
 
 SEXP watcher_create(SEXP path, SEXP recursive, SEXP callback) {
 
-  const char *watch_path = R_ExpandFileName(CHAR(STRING_ELT(path, 0)));
+  const char *watch_path = CHAR(STRING_ELT(path, 0));
   const int recurse = LOGICAL(recursive)[0];
   if (callback != R_NilValue) {
     SEXPTYPE typ = TYPEOF(callback);
@@ -93,14 +93,9 @@ SEXP watcher_create(SEXP path, SEXP recursive, SEXP callback) {
     }
   }
 
-  SEXP out, PathSymbol;
-  PathSymbol = Rf_install("path");
+  SEXP out;
   PROTECT(out = R_MakeExternalPtr(handle, R_NilValue, callback));
   R_RegisterCFinalizerEx(out, session_finalizer, TRUE);
-  Rf_setAttrib(out, PathSymbol, Rf_mkString(watch_path));
-  Rf_setAttrib(out, Rf_install("recursive"), Rf_ScalarLogical(recurse));
-  Rf_setAttrib(out, Rf_install("active"), Rf_ScalarLogical(0));
-  Rf_classgets(out, Rf_mkString("watch"));
 
   UNPROTECT(1);
   return out;
@@ -109,33 +104,21 @@ SEXP watcher_create(SEXP path, SEXP recursive, SEXP callback) {
 
 SEXP watcher_start_monitor(SEXP session) {
 
-  if (TYPEOF(session) != EXTPTRSXP)
-    return Rf_ScalarLogical(0);
-
   FSW_HANDLE handle = (FSW_HANDLE) R_ExternalPtrAddr(session);
   pthread_t thr;
 
   if (eln2 == NULL && R_ToplevelExec(load_later_safe, NULL)) {
     eln2 = (void (*)(void (*)(void *), void *, double, int)) R_GetCCallable("later", "execLaterNative2");
   }
 
-  const int started = pthread_create(&thr, NULL, &watcher_thread, handle) == 0;
-  Rf_setAttrib(session, Rf_install("active"), Rf_ScalarLogical(started));
-
-  return Rf_ScalarLogical(started);
+  return Rf_ScalarLogical(pthread_create(&thr, NULL, &watcher_thread, handle) == 0);
 
 }
 
 SEXP watcher_stop_monitor(SEXP session) {
 
-  if (TYPEOF(session) != EXTPTRSXP)
-    return Rf_ScalarLogical(0);
-
   FSW_HANDLE handle = (FSW_HANDLE) R_ExternalPtrAddr(session);
 
-  const int stopped = fsw_stop_monitor(handle) == FSW_OK;
-  Rf_setAttrib(session, Rf_install("active"), Rf_ScalarLogical(!stopped));
-
-  return Rf_ScalarLogical(stopped);
+  return Rf_ScalarLogical(fsw_stop_monitor(handle) == FSW_OK);
 
 }

man/watcher.Rd

@@ -5,24 +5,24 @@ test_that("watcher() watches", {
   dir.create(dir)
   dir.create(subdir)
   w <- watcher(dir, recursive = FALSE, callback = NULL)
-  expect_s3_class(w, "watch")
-  expect_false(attr(w, "recursive"))
-  expect_false(attr(w, "active"))
-  expect_true(watcher_start(w))
-  expect_true(attr(w, "active"))
+  expect_s3_class(w, "Watcher")
+  expect_false(w$recursive)
+  expect_false(w$active)
+  expect_true(w$start())
+  expect_true(w$active)
   Sys.sleep(1L)
   file.create(file.path(dir, "testfile"))
   Sys.sleep(1L)
-  expect_true(watcher_stop(w))
-  expect_false(attr(w, "active"))
+  expect_true(w$stop())
+  expect_false(w$active)
   w <- watcher(dir, recursive = TRUE, callback = function() x <<- x + 1L)
   expect_output(print(w))
-  expect_s3_class(w, "watch")
-  expect_true(attr(w, "recursive"))
-  expect_false(attr(w, "active"))
+  expect_s3_class(w, "Watcher")
+  expect_true(w$recursive)
+  expect_false(w$active)
   skip_if_not_installed("later")
-  expect_true(watcher_start(w))
-  expect_true(attr(w, "active"))
+  expect_true(w$start())
+  expect_true(w$active)
   Sys.sleep(1L)
   file.create(file.path(subdir, "oldfile"))
   later::run_now(2L)
@@ -42,13 +42,8 @@ test_that("watcher() watches", {
   file.remove(file.path(dir, "newfile"))
   later::run_now(2L)
   expect_equal(x, 6L)
-  expect_true(watcher_stop(w))
-  expect_false(attr(w, "active"))
+  expect_true(w$stop())
+  expect_false(w$active)
   unlink(dir, recursive = TRUE, force = TRUE)
-})
-
-test_that("watcher() error handling", {
   expect_error(watcher(callback = "callback"), "must be a function")
-  expect_false(watcher_start("test"))
-  expect_false(watcher_stop("test"))
 })