Question

I have a file under /lib with its own method.

# lib/file.rb
class File < ApplicationController
  def my_method
    ...
  end
end

However I can’t reach the method through the console

ruby-1.9.2-p290 :044 > File.my_method
NoMethodError: undefined method `my_method' for File:Class

Any idea how?

Answer 1

my_method is an instance method of the File class. It means that you can call it only on the instance of the File class.

file = File.new
file.my_method

You can declare my_method as class method using def self.my_method syntax.

class File < ApplicationController
  def self.my_method
    ...
  end
end

File.my_method

But in class methods you can’t use instance variables of the File object.