## ----include = FALSE----------------------------------------------------------
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

## ----eval=FALSE---------------------------------------------------------------
# # Load library
# library(assertions)
# 
# # Create a function that asserts input is numeric
# assert_numeric_2 <- assert_create(
#   func = is.numeric, # Returns TRUE/FALSE for assertion PASS/FAIL
#   default_error_msg = "'{arg_name}' must be of type numeric, not {class(arg_value)}"
#   )
# 
# # Assertion passes if input is numeric
# assert_numeric_2(123)
# 
# # But throws the expected error if input is not numeric
# assert_numeric_2("abc")
# 

## ----eval=FALSE---------------------------------------------------------------
# assert_string <- assert_create_chain(
#   assert_create(is.character, '{arg_name} must be a character, not {class(arg_value)}'),
#   assert_create(function(s){ length(s)==1 }, '{arg_name} must be length 1, not {arg_value}')
# )
# 
# # Assert String
# assert_string("String")
# 
# assert_string(3)
# # Output: Error: '3' must be a character

## ----eval=FALSE---------------------------------------------------------------
# # Define Function
# is_a_string <- function(object){
#  if(!is.character(object))
#    return("{arg_name} must be a character, not {class(arg_value)}")
# 
#   if(length(object) != 1){
#     return("{arg_name} must be length 1, not {length(object)}")
#   }
# 
#   return(TRUE)
# }
# 
# # Create Assertion
# assert_is_string <- assert_create(
#  is_a_string
# )
# 
# # Test assertion works
# assert_is_string("String")
# 
# assert_is_string(3)
# # 3 must be a character, not numeric
# 
# assert_is_string(c("A", "B"))