Add with_tempfile functions

Fixes #32

DESCRIPTION

@@ -41,6 +41,7 @@ Collate:
     'seed.R'
     'wrap.R'
     'sink.R'
+    'tempfile.R'
     'utils.R'
     'with.R'
 RoxygenNote: 6.0.1

NAMESPACE

@@ -15,6 +15,7 @@ export(local_output_sink)
 export(local_par)
 export(local_path)
 export(local_temp_libpaths)
+export(local_tempfile)
 export(with_)
 export(with_collate)
 export(with_dir)
@@ -30,4 +31,5 @@ export(with_path)
 export(with_preserve_seed)
 export(with_seed)
 export(with_temp_libpaths)
+export(with_tempfile)
 importFrom(stats,runif)

NEWS.md

@@ -1,5 +1,8 @@
 # devel
 
+- Add `with_tempfile()` and `local_tempfile()` functions to create temporary
+  files which are cleanup up afterwards. (#32)
+
 - Remove the `code` argument from `local_` functions (#50).
 
 # 2.0.0

R/tempfile.R

@@ -0,0 +1,31 @@
+#' Temporary files
+#'
+#' Temporarily create a tempfile, which is automatically removed afterwards.
+#' @template with
+#' @param new `[character vector]`\cr Names of temporay file handles to create.
+#' @param envir `[environment]`\cr Environment in which to define the temporary files.
+#' @inheritParams base::tempfile
+#' @export
+with_tempfile <- function(new, code, envir = parent.frame(),
+  pattern = "file", tmpdir = tempdir(), fileext = "") {
+  env <- new.env(parent = envir)
+  for (f in new) {
+    assign(f,
+      tempfile(pattern = pattern, tmpdir = tmpdir, fileext = fileext),
+      envir = env)
+  }
+  on.exit(unlink(mget(new, envir = env)))
+  eval(substitute(code), envir = env)
+}
+
+#' @rdname with_tempfile
+#' @export
+local_tempfile <- function(new, envir = parent.frame(),
+  pattern = "file", tmpdir = tempdir(), fileext = "") {
+  for (f in new) {
+    assign(f,
+      tempfile(pattern = pattern, tmpdir = tmpdir, fileext = fileext),
+      envir = envir)
+  }
+  defer(unlink(mget(new, envir = envir)), envir = envir)
+}

tests/testthat/test-tempfile.R

@@ -0,0 +1,44 @@
+context("tempfile")
+
+test_that("with_tempfile works", {
+
+  f1 <- character()
+  f2 <- character()
+
+  with_tempfile("file1", {
+    writeLines("foo", file1)
+    expect_equal(readLines(file1), "foo")
+    with_tempfile("file2", {
+      writeLines("bar", file2)
+      expect_equal(readLines(file1), "foo")
+      expect_equal(readLines(file2), "bar")
+
+      f2 <<- file2
+    })
+    expect_false(file.exists(f2))
+    f1 <<- file1
+  })
+  expect_false(file.exists(f1))
+})
+
+test_that("local_tempfile works", {
+
+  f1 <- character()
+  f2 <- character()
+
+  f <- function() {
+    local_tempfile("file1")
+    writeLines("foo", file1)
+    expect_equal(readLines(file1), "foo")
+    local_tempfile("file2")
+    writeLines("bar", file2)
+    expect_equal(readLines(file1), "foo")
+    expect_equal(readLines(file2), "bar")
+    f1 <<- file1
+    f2 <<- file2
+  }
+  f()
+
+  expect_false(file.exists(f1))
+  expect_false(file.exists(f2))
+})