The Well-Grounded Rubyist, Second Edition

2.3. The innate behaviors of an object

Even a newly created object isn’t a blank slate. As soon as an object comes into existence, it responds to a number of messages. Every object is “born” with certain innate abilities.

To see a list of innate methods, you can call the methods method (and throw in a sort operation, to make it easier to browse visually):

p Object.new.methods.sort

The result is a list of all the messages (methods) this newly minted object comes bundled with. (Warning: The output looks cluttered. This is how Ruby displays arrays—and the methods method gives you an array of method names. If you want a list of the methods one per line, use puts instead of p in the command.)

[:!, :!=, :!~, :<=>, :==, :===, :=~, :__id__, :__send__, ...