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

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = "100%"
)

options(rlang_backtrace_on_error = "none")

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)

Expressions are auto labeled

x <- 1
dclr_is_character(x)

Works with function arguments

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

fn(x)

fn(c("x", "y"))

Lots of extra helpers based on rlang goodies

dclr_has_name(mtcars, "x")

dclr_is_integerish(1.5)

dclr_is_integerish(1)

dclr_is_bool(1)

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))

# This fails because neither pass
dclr_or(dclr_is_character(x), dclr_has_name(x, "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))