assertive.base: assert_engine – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

assert_engine

Throws an error if a condition isn't met

Description

The workhorse of the package that creates an assertion from a predicate. If a condition isn't met, then an error is thrown. This function is exported for use by package developers so that they can create their own assert functions.

Usage

assert_engine(
  predicate,
  ...,
  msg = "The assertion failed.",
  what = c("all", "any"),
  na_ignore = FALSE,
  severity = c("stop", "warning", "message", "none")
)

Arguments

`predicate`	Function that returns a logical value (possibly a vector).
`...`	Passed to the `predicate` function.
`msg`	The error message, in the event of failure.
`what`	Either 'all' or 'any', to reduce vectorised tests to a single value.
`na_ignore`	A logical value. If `FALSE`, `NA` values cause an error; otherwise they do not. Like `na.rm` in many stats package functions, except that the position of the failing values does not change.
`severity`	How severe should the consequences of the assertion be? Either `"stop"`, `"warning"`, `"message"`, or `"none"`.

Value

FALSE with the attribute message, as provided in the input.

Note

Missing values are considered as FALSE for the purposes of whether or not an error is thrown.

Examples

# Basic usage is like do.call; pass a predicate and the arguments to it.
dont_stop(assert_engine(is_true, c(TRUE, FALSE, NA)))

# Customise the error message
dont_stop(
  assert_engine(is_true, c(TRUE, FALSE, NA), msg = "Not everything is true")
)

# Only fail when no values match the predicate's conditions
dont_stop(assert_engine(is_true, logical(3), what = "any"))

# You can use base predicates, but the error message isn't as informative
dont_stop(assert_engine(is.matrix, 1:5))

# Reduce the severity of failure
assert_engine(is_true, c(TRUE, FALSE, NA), severity = "message")

assertive.base

A Lightweight Core of the 'assertive' Package

v0.0-9

GPL (>= 3)

Authors

Richard Cotton [aut, cre], Sunkyu Choi [trl], Ivanka Skakun [trl], Gergely Dar<c3><b3>czi [trl], Anton Antonov [trl], Hisham Ben Hamidane [trl], Anja Billing [trl], Aditya Bhagwat [trl], Rasmus B<c3><a5><c3><a5>th [trl], Mine Cetinkaya-Rundel [trl], Aspasia Chatziefthymiou [trl]

Initial release

2021-02-07