6.9 Respect the R landscape

As people will use your package in many situations you should avoid editing the global settings, so we should avoid applying any of the functions in R/:

• Loading a package with library() or require().
• Loading code with source().
• Changing a global option with options().
• Modifying the working directory with setwd().
• Specifying seeds for creating random numbers with set.seed().
• Setting graphical parameters with par().
• Setting environment variable with Sys.setenv().
• Setting aspects of the locale with Sys.setlocale().

If you must use them, make sure to clean up after yourself.