Validate Input

Source: vignettes/details/validate_arguments.Rmd

validate_arguments decorator allows the arguments passed to a function to be parsed and validated using the function’s annotations before the function is called.

How It Works

validate_arguments provides an extremely easy way to apply validation to your code with minimal boilerplate. The original function needs to have key-value pairs in its declaration, where the each value carries its designated class.

When to Use It

  • To protect functions from receiving unexpected types of input arguments.
  • In ValueObjects.

Examples: Functions with Built-in NA classes

Given a Customer ValueObject

Customer <- function(given = NA_character_, family = NA_character_)
    return(data.frame(given = given, family = family))

When Customer is decorated with validate_arguments

Customer <- validate_arguments(Customer)

Then passing arguments of any type other then the declared type prompts an informative error.

In the Customer example, both input arguments given and family are declared as character.

Customer(given = "Bilbo", family = "Baggins") # Works as both arguments are character
#>   given  family
#> 1 Bilbo Baggins
try(Customer(given = "Bilbo", family = 90201)) # Fails because family is not a character
#> Error in Customer(given = "Bilbo", family = 90201) : 
#>   family is of type `numeric` rather than `character`!