This package provides backports of functions which have been introduced in one of the base packages in R version 3.0.1 or later. The backports are conditionally exported in order to let R resolve the function name to either the implemented backport, or the respective base version, if available. Package developers can make use of new functions or arguments by selectively importing specific backports to support older installations.
Attach the namespace via library(backports)
.
Note that it is crucial that backports
is build against the currently running R version.
Do not ignore these kind of warnings for this package.
- Add backports to your DESCRIPTION under
Imports
. - Add or modify the function
.onLoad()
(see here) to call theimport()
function of backports:You can also selectively import functions:.onLoad <- function(libname, pkgname) { backports::import(pkgname) }
If you set.onLoad <- function(libname, pkgname) { backports::import(pkgname, c("get0", "dir.exists")) }
force = TRUE
, the provided functions will get imported, regardless of the R version:.onLoad <- function(libname, pkgname) { backports::import(pkgname, "hasName", force = TRUE) }
- [Optional] Set
Depends
in your DESCRIPTION to requireR (>= 3.0.0)
.
Backports for functions which are not in the base
require additional steps.
Usually, you need to to import those functions in the package NAMESPACE.
However, this is only possible if such a function really exists, and yields a warning during R CMD check
for older versions.
There are three possibilities to deal with this:
- Completely import the namespaces instead of selectively importing them, e.g. use
import(utils)
instead ofimportFrom(utils, hasName)
in yourNAMESPACE
file. - Force-import the function (see above) so that you always use the backport instead of the implementation shipped with R, even for the most recent version of R.
- Use a conditional import in your
NAMESPACE
file, e.g.if (getRversion() >= "3.4.0") { importFrom(utils, hasName) } else { importFrom(backports, hasName) }
Note that the braces {}
are necessary in the
NAMESPACE
file, even though they wouldn't be for regular R code, and that you might get a warning
for including backports
in the Imports:
section of your DESCRIPTION
file if you never end up using it.
base::anyNA()
base::dir.exists()
base::file.size()
,base::file.mode()
andbase::file.mtime()
base::lengths()
- Argument
extra_cols
forbase::file.info()
- Argument
repeated
forutils::URLencode
base::isNamespaceLoaded()
base::startsWith()
andbase::endsWith()
base::strrep()
base::trimws()
- Argument
type
forutils::capture.output()
base::.valid.factor()
utils::hasName()
base::...length()
base::...elt()
base::isFALSE()
base::warningCondition()
base::errorCondition()
- Argument
q
forbase::dQuote()
andbase::sQuote()
tools::vignetteInfo()
base::str2lang()
base::str2expression()
base::asplit()
utils::removeSource()
with the capability to strip source from language objects.
base::deparse1()
base::list2DF()
tools::R_user_dir()
- Argument
classes
forbase::suppressWarnings()
andbase::suppressMessages()
- Argument
recycle0
forbase::paste()
. - Argument
recycle0
forbase::paste0()
.
base::...names()
tools:::print.Rconcordance
tools:::as.character.Rconcordance
tools::as.Rconcordance
tools:::as.Rconcordance.default
tools::matchConcordance