file.py

class File:
    file_count = 0

    def __init__(self, name):
        self.file_name = name
        # self.file_count = 1
        self.__class__.file_count += 1

f1 = File(__file__)
f2 = File(__file__)

print('f1.file_count = ', f1.file_count)
print('f2.file_count = ', f2.file_count)
print('File.file_count = ', File.file_count)

# f1.file_count =  2
# f2.file_count =  2
# File.file_count =  2

file.rb

class File
  @file_count = 0

  class << self
    attr_accessor :file_count
  end

  attr_reader :file_name, :file_count

  def initialize(name)
    @file_name = name
    #@file_count = 1
    self.class.file_count += 1
  end
end

f1 = File.new(name=__FILE__)
f2 = File.new(name=__FILE__)

print "f1.file_count = ", f1.file_count, "\n"
print "f2.file_count = ", f2.file_count, "\n"
print "File.file_count = ", File.file_count, "\n"

# f1.file_count =
# f2.file_count =
# File.file_count = 2