Nothing
# check labels for various arguments.
check.label = function(arg, choices, labels, argname, see) {
if (!is.string(arg))
stop("the ", argname, " must be a single character string.")
if (arg %in% choices)
return(invisible(NULL))
# concatenate valid values, optinally with labels.
if (missing(labels)) {
choices = paste(paste('"', choices, '"', sep = ""), collapse = ", ")
}#THEN
else {
labels = paste("(", labels[choices], ")", sep = "")
choices = paste('"', choices, '"', sep = "")
nl = length(labels)
choices = paste(choices, labels, collapse = ", ")
}#THEN
# mention the most relevant manual page.
if (missing(see))
see = character(0)
else
see = paste(" See ?", see, " for details.", sep = "")
# build the error message.
errmsg = paste("valid ", argname, "(s) are ", choices, ".", see, sep = "")
# make sure the error message is not truncated if possible at all.
errlen = unlist(options("warning.length"), use.names = FALSE)
options("warning.length" = max(1000, min(8170, nchar(errmsg) + 20)))
on.exit(options("warning.length" = errlen))
stop(errmsg)
}#CHECK.LABEL
# warn about unused arguments.
check.unused.args = function(dots, used.args) {
if (is(dots, "list"))
args = names(dots)
else
args = dots
unused = args %!in% used.args
if (any(unused))
warning("unused argument(s):", paste0(" '", args[unused], "'"), ".")
}#CHECK.UNUSED.ARGS
# check whether a package is loaded.
check.and.load.package = function(pkg) {
# silence all warnings while looking for suggested packages.
warning.level = as.numeric(options("warn"))
options("warn" = -1)
on.exit(options("warn" = warning.level))
if (!requireNamespace(pkg))
stop("this function requires the ", pkg, " package.")
}#CHECK.AND.LOAD.PACKAGE
# reverse lookup for optional arguments.
has.argument = function(label, arg, lookup) {
arg %in% lookup[[label]]
}#HAS.ARGUMENT
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