Assert an argument has known prototype and/or size

Source: R/assert.R

  • vec_is() is a predicate that checks if its input conforms to a prototype and/or a size.

  • vec_assert() throws an error when the input doesn't conform.

vec_assert(x, ptype = NULL, size = NULL,
  arg = as_label(substitute(x)))

vec_is(x, ptype = NULL, size = NULL)

Arguments

x

A vector argument to check.
ptype

Prototype to compare against. If the prototype has a class, its vec_type() is compared to that of x with identical(). Otherwise, its typeof() is compared to that of x with ==.
size

Size to compare against
arg

Name of argument being checked. This is used in error messages. The label of the expression passed as x is taken as default.

Value

vec_is() returns TRUE or FALSE. vec_assert() either throws a typed error (see section on error types) or returns x, invisibly.

Error types

  • If the prototype doesn't match, an error of class "vctrs_error_assert_ptype" is raised.

  • If the size doesn't match, an error of class "vctrs_error_assert_size" is raised.

Both errors inherit from "vctrs_error_assert".