validate_that is an alternative to the function
assert_that, that returns a character vector. This
makes them easier to use within S4 "validate" methods.
Usage
validate_that(..., env = parent.frame())
Arguments
...
unnamed expressions that describe the
conditions to be tested. Rather than combining
expressions with &&, separate them by commas so
that better error messages can be generated.
env
(advanced use only) the environment in which
to evaluate the assertions.
Value
A character vector if the assertion is false, or TRUE
if the assertion is true.
See Also
assert_that, which returns an error if the condition
is false.
Examples
x <- 1
# assert_that() generates errors, so can't be usefully run in
# examples
validate_that(is.numeric(x))
validate_that(is.character(x))
validate_that(length(x) == 3)
validate_that(is.dir("asdf"))