Why is Ruby seeing `A.run` in class B as a constant and not a class? - ruby

Question

so this is my first question on stack overflow and I am new to Ruby, so if this is a simple question, please be nice.
I am starting off in OOP and making a game. What I think is wrong is that Ruby is thinking that a different class is a constant in the current class.
Here is my code:
./a.rb
require "./b"
class A
class << self
def run
puts "A ran."
end
end
end
./b.rb
class B
require './a'
def test
A.run
end
end
b = B.new
b.test
When I run ruby b.rb, I get:
/Users/alexstriff/Dropbox/Code/ruby/ex45/b.rb:5:in `test': uninitialized constant B::A (NameError)
from /Users/alexstriff/Dropbox/Code/ruby/ex45/b.rb:11:in `<top (required)>'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
from /Users/alexstriff/Dropbox/Code/ruby/ex45/a.rb:1:in `<top (required)>'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/rubygems/core_ext/kernel_require.rb:45:in `require'
from b.rb:2:in `<class:B>'
from b.rb:1:in `<main>'
So why is A.run seen as a constant by class B, instead of as a class?
Edit:
Could it possibly be a problem with the 'circular require'? I ran this under ruby -w and that came up.

Answer 1

Yes, as you mentioned in your edit, I believe your issue is with a circular require. As you can see, when you run ruby b.rb, you require a.rb, which then requires b.rb again, etc. Instead, I would advise removing the require in a.rb, as it does not seem to depend on b.rb.
As a separate issue, I think the error you are getting is because you don't specify that A is a top-level class. Also, having the require inside of class B does not make A accessible inside B, so I would move it outside instead:
require './a'
class B
def test
::A.run
end
end
b = B.new
b.test