R/print_message.R

In pobsteta/theia2r: An R toolbox to find, download and preprocess Sentinel-2 data

#' @title Print a message
#' @description A common interface for printing messages of several types.
#' @details Several functions print messages in different formats
#'  (message, error, warning, cat, R output) and with different syntaxes
#'  (concatenating parameters or accepting a single argument, appending
#'   a new line, etc.).
#'   This accessory function provides a common interface for different types:
#'   several arguments are accepted and concatenated with the `sep` argument;
#'   the format is defined with the `format` argument; a date is optionally
#'   placed before the message.
#' @param ... `R` objects which are concatenated.
#' @param type Type of the output .Accepted values: 
#'  - 'message' for a diagnostic message;
#'  - 'string' for a character output;
#'  - 'cat' for the output of \code{\link[base]{cat}} function;
#'  - 'error' and 'warning' for an error or warning message. 
#'  
#'  Intentionally, no default value is defined.
#' @param sep (optional) character used to separate input values
#'  (default is nothing).
#' @param date Logical value: set TRUE to place the date before the message
#'  (useful for logs or time consuming operations); default is FALSE.
#' @param date_format Format of the date (see \code{\link[base]{strftime}})
#'  for the definition of the format). The default format is
#'  '\%Y-\%m-\%d \%H:\%M:\%S'.
#' @return Message (in the defined format).
#'
#' @author Luigi Ranghetti, phD (2017) \email{ranghetti.l@@irea.cnr.it}
#' @note License: GPL 3.0

print_message <- function(..., type, sep = "", date = FALSE, date_format = "") {
    message_string <- paste(if (date) {
        paste0("[", strftime(Sys.time(), format = date_format), "]")
    }, paste(c(...), collapse = sep))
    switch(type, message = message(message_string), string = message_string, cat = cat(message_string, "\n", sep = ""), error = stop(message_string, call. = FALSE), 
        warning = warning(message_string, call. = FALSE), waiting = invisible(readline(message_string)), stop(paste0("Type '", type, "' not yet supported.")))
}