R/ammoc.R

In crowding/vadr: Macros, metaprogramming, and pleasant programming idioms.

#' Evaluate all arguments in order, but return the first.
#'
#' Useful in where you want to clean up after a computation but but
#' return the result of the computation, as in \code{ammoc(x, rm(x))},
#' or \code{ammoc(readLines(file), close(file))}.
#' It's the reverse of the C comma operator. There is an infix alias,
#' \code{\%\'\%}, (i.e., inverted comma; use whichever you feel a
#' worse pun.)
#'
#' @note In most Lisps, this is called \code{prog1}.
#' @param ... any number of arguments.
#' @aliases %'%
#' @rdname ammoc
#' @return The first argument.
#' @author Peter Meilstrup
#' @export
ammoc <- function (...) list(...)[[1]]

#' @export "%'%"
#' @rdname ammoc
#' @usage x %'% y
`%'%` <- ammoc