Class Variable Usage in Ruby - Counter

2017-08-25

类变量的用法之计数

注意：可能会有数据竞争问题。

class HelloCount
  @@count = 0
  def self.count
    @@count
  end

  def initialize(myname="Ruby")
    @name = myname
  end

  def hello
    @@count += 1
    puts "Hello, world, I am #{@name}"
  end
end


bob = HelloCount.new("Bob")
alice = HelloCount.new("Alice")
ruby = HelloCount.new

p HelloCount.count

bob.hello
alice.hello
ruby.hello

p HelloCount.count


# 0
# Hello, world, I am Bob
# Hello, world, I am Alice
# Hello, world, I am Ruby
# 3