Merge pull request #489 from r2evans/feature/extlib_no_package

change with_extlib to work without packages

NEWS.md

@@ -1,5 +1,10 @@
 # Packrat 0.5.0 (UNRELEASED)
 
+- `packrat::with_extlib()` now works with no `packages` provided;
+  both with and without this option, the new behavior is that `expr`
+  is executed in an environment where the original (not packrat)
+  library search path is in place.
+
 - A project is now only considered 'packified' if it has both a Packrat
   lockfile as well as the associated autoloader in the project `.Rprofile`.
 

R/external.R

@@ -5,23 +5,34 @@
 ##' libraries; that is, the libraries that would be available upon launching a new
 ##' \R session.
 ##'
-##' @param packages A set of package names (as a character vector) to load for
-##'   the duration of evaluation of \code{expr}.
+##' @param packages An optional set of package names (as a character
+##'   vector) to load for the duration of evaluation of \code{expr}.
+##'   Whether \code{packages} is provided or \code{NULL} (the
+##'   default), \code{expr} is evaluated in an environment where the
+##'   external library path is in place, not the local (packrat)
+##'   library path.
 ##' @param expr An \R expression.
 ##' @param envir An environment in which the expression is evaluated.
 ##' @name packrat-external
 ##' @rdname packrat-external
 ##' @examples \dontrun{
 ##' with_extlib("lattice", xyplot(1 ~ 1))
+##' with_extlib(expr = packageVersion("lattice"))
+##' # since devtools requires roxygen2 >= 5.0.0 for this step, this
+##' # should fail unless roxygen2 is available in the packrat lib.loc
+##' with_extlib("devtools", load_all("path/to/project"))
+##' # this method will work given roxygen2 is installed in the
+##' # non-packrat lib.loc with devtools
+##' with_extlib(expr = devtools::load_all("path/to/project"))
 ##' }
 ##' @export
-with_extlib <- function(packages, expr, envir = parent.frame()) {
+with_extlib <- function(packages = NULL, expr, envir = parent.frame()) {
 
   # need to force this promise now otherwise it will get evaluated
   # in the wrong context later on
   force(envir)
 
-  if (!is.character(packages)) {
+  if (!is.null(packages) && !is.character(packages)) {
     stop("'packages' should be a character vector of libraries", call. = FALSE)
   }
 
@@ -34,11 +45,13 @@ with_extlib <- function(packages, expr, envir = parent.frame()) {
       oldSearch <- search()
 
       libPaths <- .packrat_mutables$get("origLibPaths")
+      oldLibPaths <- .libPaths()
       if (!length(libPaths))
         libPaths <- getDefaultLibPaths()
+      .libPaths(libPaths)
 
       for (package in packages) {
-        library(package, character.only = TRUE, lib.loc = libPaths, warn.conflicts = FALSE)
+        library(package, character.only = TRUE, warn.conflicts = FALSE)
       }
 
       ## Evaluate the call
@@ -57,6 +70,7 @@ with_extlib <- function(packages, expr, envir = parent.frame()) {
       for (path in setdiff(newSearch, oldSearch)) {
         try(forceUnload(path))
       }
+      .libPaths(oldLibPaths)
     })
 
   })

tests/testthat/test-with_extlib.R

@@ -0,0 +1,24 @@
+context("extlib without packages")
+
+test_that("with_extlib successfully works with no packages provided", {
+
+  ## Make sure packrat mode is off
+  if (packrat:::isPackratModeOn())
+    packrat::off()
+
+  orig_libs <- packrat:::getLibPaths()
+  .libPaths(c(file.path(getwd(), "packages"), orig_libs))
+  on.exit(.libPaths(orig_libs), add = TRUE)
+
+  expect_identical(packageVersion("bread"), package_version("1.0.0"))
+
+  # don't use packrat::on so we can avoid the initialization step
+  packrat:::setPackratModeOn(auto.snapshot = FALSE, clean.search.path = FALSE)
+
+  expect_error(packageVersion("bread"), "package 'bread' not found")
+
+  expect_identical(packrat::with_extlib(expr = packageVersion("bread")), package_version("1.0.0"))
+
+  packrat::off()
+
+})