Functions introduced or changed since R v3.0.0 are re-implemented in this package. 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.
.valid.factor()for R versions prior to 3.4.0.
...elt()for R versions prior to 3.5.0.
isFALSE()for R versions prior to 3.5.0.
import(). This is now the recommended way to use backports non-interactively. Simply importing backports in the NAMESPACE still works, but is comparably error-prone if the same library is used by multiple R installations.
get0()for R versions prior to 3.2.0.
hasName()for R versions prior to 3.4.0.
file.info()with backport for argument
file.mode()for R versions prior to 3.2.0.