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Validation - Throw error from custom predicate

assert_predicate.Rd

This function evaluates a custom predicate function on an object and aborts with a custom message if the check fails. It is useful for testing function arguments.

Usage

assert_predicate(
  fun,
  ...,
  args_fun = list(),
  msg = NULL,
  x_names = NULL,
  env = caller_env(),
  args_cnd = list()
)

Arguments

fun

[\(){}] The predicate function to run. Must receive the object to test as its first argument.

...

[any each] Objects to check.

args_fun

[list()] Additional arguments to pass to fun.

msg

[character(1) | NULL] The message to use if the check fails. If NULL, a default message is generated.

x_names

[character() | NULL] The names of ... to print in messages. If NULL, the name is inferred from ...'s expressions.

env

[environment() | call() | NULL | missing_arg()] The call to inform as the origin of the error, passed to rlang::abort():

  • An environment in the call stack or a hard-coded defused call.

  • NULL for no information.

  • missing_arg() to use the assert function itself.

  • The default is caller_env(), to display the function where the assertion was called.

args_cnd

[list()] Additional arguments passed to cli::cli_abort().

Value

[list(...)] invisible(list(...)), or aborts if the check fails.

Examples

try({
  f <- \(x) test_when(x, all(.x > 0))
  f(c(-1, 0, 1))
})
#> Error in test_when(x, all(.x > 0)) : could not find function "test_when"
#> Error in `f()`:
#> ! Argument `x` fails `all(.x > 0)`.