Functions

Structure

Name

Arguments

• nouns
• options that modify how the function runs

Body

Return

Structure

name <- function(arguments) {
  body

  return()
}

Naming

snake_case

verb_noun

• plot_cars()
• count_trees()
• model_elephants()

Planning

Define inputs, outputs

Functions should strive to do one thing, with no side effects

• a common exemption is writing files or generating plots

Checks

Make sure users provide appropriate inputs and arguments

Handle errors with informative errors

• stopifnot()
• stop()
• warning()
• message()

Control flow

Manage choices, if something do this, else do this

• if()
• else()
• ifelse()

Testing/approach

Simple approach

• testing scripts
• interactive tests

Extended approach

• full testing suites with {testthat} or {tinytest}