R/logical_or.R

In toniprice/jute: Sundry Utility Functions

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#' Logical \code{OR} operator
#'
#' Sets default values using a logical \code{OR} operator.
#'
#' @name logical_OR
#'
#' @param a NULL, or a specific value.
#' @param b The default value to return if the first operand is NULL.
#'
#' @return A non-NULL value. This is is the value of the first operand if it is
#'   non-NULL, or the value of the second operand if the first operand is NULL.
#'
#' @details
#' This infix function is inspired by Ruby's "logical OR" operator (\code{||})
#' for conveniently setting default values.\cr
#'
#' usage:\cr
#' \code{function_that_might_return_null() \%||\% <default value>}
#'
#' See Advanced R (Hadley Wickham) Section 6.5.1 p. 91.
#'
#' @references
#'   Wickham, Hadley (2015). Advanced R, CRC Press, Boca Raton FL.
#' @examples
#' x <- NULL
#' x %||% 10 # => 10
#'
#' x <- NULL
#' y <- "Nelson Mandela"
#' x %||% y # => 'Nelson Mandela'
#'
#' x <- "Madiba"
#' y <- "Nelson Mandela"
#' x %||% y # => 'Madiba'
#'
#' @export
#'
`%||%` <- function(a, b) {
  if (!is.null(a)) a else b
}

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