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我的期望值在评论中。如何添加一个扩展classmethods并正确引用类的模块var
require 'logger'
module Logging
attr_accessor :logger
def logger
return @logger if @logger # allow items to have own loggers
@@logger ||= Logger.new(STDERR)
puts "Instance Class REF ID#{@@logger.__id__}"
puts "Class ID #{self.class.logger.__id__}"
@@logger
end
module ClassMethods
def logger= logger
@logger = logger
end
def logger
@logger ||= Logger.new(STDERR)
puts "Class Instance REF ID #{@logger.__id__}"
@logger
end
end
def self.included(base)
base.extend(ClassMethods)
end
end
class Test
include Logging
def wow
logger.info 'wow'
end
end
t = Test.new
# should be the same
puts "Loggers are #{t.logger.__id__ == Test.logger.__id__ ? '' : 'not '}the same"
Test.logger = Logger.new('/dev/null')
# should still be the same
puts "Loggers are #{t.logger.__id__ == Test.logger.__id__ ? '' : 'not '}the same"
lg = Test.logger.__id__
t.logger = Logger.new(STDERR)
# class logger should be same
puts "Class Logger is #{Test.logger.__id__ == lg ? 'still the' : 'not'} same"
# class and instance logger should be different
puts "Loggers are #{t.logger.__id__ == Test.logger.__id__ ? '' : 'not '}the same"
执行时:
➜ sandbox irb 1.9.3-p392 :001 > load 'test_l.rb' Instance Class REF ID70203753590760 Class Instance REF ID 70203753590500 Class ID 70203753590500 Class Instance REF ID 70203753590500 Loggers are not the same # I expected to be same... :( Instance Class REF ID70203753590760 Class Instance REF ID 70203753590000 Class ID 70203753590000 Class Instance REF ID 70203753590000 Loggers are not the same # I expected to be same... :( Class Instance REF ID 70203753590000 Class Instance REF ID 70203753590000 Class Logger is still the same Class Instance REF ID 70203753590000 Loggers are not the same
请考虑编辑标题变得有用。 – Anna 2013-03-07 14:48:47
您的标题需要反映您提问的问题。因为它是毫无价值的。 – 2013-03-07 14:56:52
学习为变量和方法使用更好/更具描述性的名称。就目前而言,六个月后,你将很难保持头脑清醒。不要在main和class级别重用实例和类变量AND方法的相同名称。 – 2013-03-07 15:01:00