Run Code if Current File is Calling File
This conditional tells Ruby to execute the code within if the current file is the file running the code.
# exec.rb if __FILE__ == $0 puts 'shown when exec.rb is run directly; not when required' end
This works by comparing the current file (
__FILE__) with the file that started the program (
$0). If they aren't the same (
exec.rb), the statement will not be printed.