README.md

In DavisVaughan/declair: What the Package Does (One Line, Title Case)

declair

The goal of declair is to provide standardized validation functions. It is inspired by vctrs::vec_assert() and motivated by frustration and duplication across packages when validating user input.

Installation

You can install the released version of declair from CRAN with:

# no you cannot
install.packages("declair")

devtools::install_github("DavisVaughan/declair")

Example

library(declair)

Nice error messages based on type

dclr_is_character(1)
#> Error: `1` must be <chr>, not <dbl>.

Expressions are auto labeled

x <- 1
dclr_is_character(x)
#> Error: `x` must be <chr>, not <dbl>.

Works with function arguments

fn <- function(my_arg) {
  dclr_is_scalar_character(my_arg)
}

fn(x)
#> Error: `my_arg` must be <chr>, not <dbl>.

fn(c("x", "y"))
#> Error: `my_arg` must have size 1, not size 2.

Lots of extra helpers based on rlang goodies

dclr_has_name(mtcars, "x")
#> Error: `mtcars` must have name 'x'.

dclr_is_integerish(1.5)
#> Error: `1.5` must be integerish.

dclr_is_integerish(1)

dclr_is_bool(1)
#> Error: `1` must be <bool> (TRUE / FALSE), not <dbl>.

Combine multiple checks with dclr_or() and dclr_and()

x <- 1L

# All good because the second condition passes
dclr_or(dclr_is_character(x), dclr_is_integer(x))

# This fails and tells you which condition caused the issue
dclr_and(dclr_is_character(x), dclr_is_integer(x))
#> Error: All conditions must pass. The following do not:
#> - `x` must be <chr>, not <int>.

# This fails because neither pass
dclr_or(dclr_is_character(x), dclr_has_name(x, "a name"))
#> Error: At least one condition must pass:
#> - `x` must be <chr>, not <int>.
#> - `x` must have name 'a name'.

dclr_or() is particularly useful if an argument defaults to NULL but can be other things.

x <- NULL

# All good
dclr_or(dclr_is_character(x), dclr_is_null(x))

x <- "hi"

# All good
dclr_or(dclr_is_character(x), dclr_is_null(x))

# Not good!
x <- TRUE

dclr_or(dclr_is_character(x), dclr_is_null(x))
#> Error: At least one condition must pass:
#> - `x` must be <chr>, not <lgl>.
#> - `x` must be NULL.

You can use dclr() on any custom ptype and size.

dclr(1, ptype = glue::glue(), size = 1)
#> Error: `1` must be <glue>, not <dbl>.

DavisVaughan/declair documentation built on May 17, 2019, 8:20 p.m.