New class definition and scope resolution operator

Question

I make a simple Ruby class as follows in a Ruby script:

class Rock::Stone
end

When I run the script at the command prompt, I get:

`<main>': uninitialized constant Rock (NameError)

Why is this? I thought scope resolution operators were allowed in class defs?

Answer 1

I thought scope resolution operators were allowed in class defs?

They are allowed, but the containing module (or class) must exist first:

module Rock
end

class Rock::Stone
end

Rock::Stone.new
# => #<Rock::Stone:0x00000000a38248>

Answer 2

The encapsulating module/class must be declared first. Try this:

module Rock
  class Stone
  end
end

Answer 3

I think you might need to create a class or module Rock first, then Rock::Stone can exist.

This SO thread may help.