Assert input is a list — assert_list • assertions

Assert input is a list

Usage

assert_list(
  x,
  include_dataframes = FALSE,
  msg = NULL,
  call = rlang::caller_env(),
  arg_name = NULL
)

Arguments

x: An object
include_dataframes: A logical indicating whether data_frames should be considered vectors. Default is FALSE.
msg: A character string containing the error message to display if x is not a list
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 list, otherwise aborts with the error message specified by msg

Examples

try({
# Assert that a variable is a list
x <- list(1, 2, 3)
assert_list(x)  # does nothing

# Assert that a variable is not a list
x <- "not a list"
assert_list(x)  # stops execution and prints an error message
})
#> Error in eval(expr, envir) : 
#>   'x' must be a list, not a character