Question

I have come across two methods of calling a file class: File and ::File

Can someone explain to me the difference between the two, and also the separate reasons for using the two?

Answer 1

File refers to the File constant in the current scope, while ::File always refers to Object::File.

p File
# File

p ::File
# File

module Another
  module File
  end

  p File
  # Another::File

  p ::File
  # File
end

Thus, the :: is analogous to the root of a file system and the module you are in is analogous to the current directory.

For object-oriented access to the current lexical scope, see Module.nesting.