Ruby’s secret file

Ruby has a secret input stream hidden in every source file.

The ruby interpreter stops parsing the source file when it hits the sentinel marker __END__ like this:

puts 'hello Billy'
__END__
Nothing after this line is parsed

#=> hello Billy

But that's not the end of the story. Everything after the __END__ is still available as an inputstream via the predefined constant DATA. Let's see:

puts DATA.read
__END__
The good ship Bellerophon

#=> The good ship Bellerophon

A little cryptic to be a whole heap of use but perhaps useful for generating default configuration settings perhaps.