Modify the behaviour of type checking functions

Modify the type-checking, or length-checking behaviour of favr type checking functions.

Usage

bare(x, arg = caller_arg(x))

at_least(n, arg = caller_arg(n))

at_most(n, arg = caller_arg(n))

in_range(
  n_min,
  n_max,
  arg_min = caller_arg(n_min),
  arg_max = caller_arg(n_max)
)

Arguments

x: An object to modify the check behaviour for.
arg, arg_min, arg_max: An argument name as a string. This argument will be mentioned in error messages as the input that is at the origin of a problem.
n, n_min, n_max: Single numeric value that is castable to an integer. Must be zero or positive.

Value

A list of class favr_modifier with named elements obj, bare and arg for bare(), and at_least and/or at_most for the length modifiers.

Details

Use bare() to check if a given object is a bare R object (no class attribute, see is.object()), throwing an error if it is not and passing the object on to the check if it is.

For S3 type checks, bare() checks that the object has the expected S3 type as the first element of the class vector.

To modify the behaviour of length checking arguments n, nrow, and ncol (example described for n):

at_least(n) means the object must be at least length (>=) n.
at_most(n) means the object must be at most length (<=) n.
in_range(n_min, n_max) means the object length must be within the range of (>=) n_min and (<=) n_max.

Examples

bare(1)
#> $obj
#> [1] 1
#> 
#> $bare
#> [1] TRUE
#> 
#> $arg
#> [1] "1"
#> 
#> attr(,"class")
#> [1] "favr_bare"     "favr_modifier"
at_least(1)
#> $at_least
#> [1] 1
#> 
#> attr(,"class")
#> [1] "favr_at_least" "favr_modifier"
at_most(1)
#> $at_most
#> [1] 1
#> 
#> attr(,"class")
#> [1] "favr_at_most"  "favr_modifier"
in_range(1, 2)
#> $at_least
#> [1] 1
#> 
#> $at_most
#> [1] 2
#> 
#> attr(,"class")
#> [1] "favr_in_range" "favr_modifier"

at_least(1.5) |> try()
#> Error in at_least(1.5) : 
#>   Can't convert from `1.5` <double> to `at_least 'n'` <integer> due to loss of precision.
#> • Locations: 1

check_integer(bare(factor(1))) |> try()
#> Error in eval(expr, envir) : 
#>   `factor(1)` must be a bare <integer>, but it is of class <factor>.
check_integer(1:5, n = at_least(10)) |> try()
#> Error in eval(expr, envir) : 
#>   `1:5` must be an <integer> vector of at least length 10, but it is of
#> length 5.
check_integer(1:5, n = at_most(3)) |> try()
#> Error in eval(expr, envir) : 
#>   `1:5` must be an <integer> vector of at most length 3, but it is of
#> length 5.
check_integer(1:5, n = in_range(2, 4)) |> try()
#> Error in eval(expr, envir) : 
#>   `1:5` must be an <integer> vector of a length between 2 and 4, but it is
#> of length 5.

x <- as.Date("2000-01-01")
class(x) <- c("my_date", class(x))
check_date(bare(x)) |> try()
#> Error in eval(expr, envir) : 
#>   `x` must be a bare <Date>, but it is of class <my_date>.