R/nn.R

In pobsteta/shiny-cnes: Package to download space image from CNES server (theia, peps...)

#' @title Replace NULL with character()
#' @description Internal function: return character(0) instead of NULL.
#'  This is sometimes needed not to return error when applying some functions.
#' @param x Input variable
#' @return `character(0)` if `x==NULL`, `x` elsewhere
#' @author Luigi Ranghetti, phD (2017) \email{ranghetti.l@@irea.cnr.it}
#' @note License: GPL 3.0
#'
#' @examples
#' \dontrun{
#' basename(NULL) # error
#' basename(character()) # ok
#' basename(nn(NULL)) # ok
#' }
#' 
nn <- function(x) {
  if (is.null(x)) {
    character(0)
  } else {
    x
  }
}

# # Version which replaces also non-existing objects nn <- function(x) { if (!exists(deparse(substitute(x)))) { character(0) } else if (is.null(x)) { character(0) }
# else { x } }