assert_flag: Assert input is a scalar logical

In assertions: Simple Assertions for Beautiful and Customisable Error Messages

Assert input is a scalar logical

Description

Assert input is a flag (a logical of length 1: TRUE or FALSE)

Usage

assert_flag(x, msg = NULL, call = rlang::caller_env(), arg_name = NULL)

Arguments

x	An object
msg	A character string containing the error message to display if x is not a scalar logical
call	Only relevant when pooling assertions into multi-assertion helper functions. See cli_abort for details.
arg_name	Advanced use only. Name of the argument passed (default: NULL, will automatically extract arg_name).

Value

invisible(TRUE) if x is a scalar logical, otherwise aborts with the error message specified by msg

Examples

try({
assert_flag(TRUE) # Passes
assert_flag(FALSE) # Passes
assert_flag(c(TRUE, FALSE)) # Throws default error
assert_flag(1, "Custom error message") # Throws custom error
})

assertions documentation built on April 3, 2025, 5:52 p.m.