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Validate a Logical Flag

Source: R/checks.R
checkFlag.Rd

Checks that an argument is a single non-missing TRUE or FALSE. Meant for the many switches in the suite - correct, unbiased, scaled, paired and the like - which were previously either unchecked or checked in three different ways.

Usage

checkFlag(x, name = deparse(substitute(x)))

Arguments

x

the value to check.

name

the argument name to use in the message. Defaults to the expression that was passed, which is right in the ordinary case checkFlag(correct); supply it explicitly when the caller passes something else, e.g. checkFlag(args$correct, "correct").

Value

x, invisibly.

Details

NA is rejected on purpose. It is a logical of length one and therefore passes is.logical(), but a flag that is neither on nor off has no meaning for a switch - and it propagates silently, because if (NA) is an error somewhere further down rather than here.

See also

checkConfLevel(), checkCount(), checkString()

Examples

correct <- TRUE
checkFlag(correct)

if (FALSE) { # \dontrun{
correct <- NA
checkFlag(correct)             # "'correct' must be a single ..."
} # }