Why ENV behave like a hash, but it's an Object class

Question

Am I right to consider ENV a Hash

ENV['HOME']

=>'/Users/yozloy'

But

ENV.class

#=>Object

Answer 1

It implements most of the Hash methods but apparently a few are missing:

[:default, :default=, :default_proc, :default_proc=, :merge!, :merge, :flatten, :compare_by_identity, :compare_by_identity?]

Most of these you'd never think to use, but merge and flatten could be useful.

Remember that ENV isn't exactly a Hash, but a wrapper around the environment variables and the associated methods for retrieving and setting them.