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Asked: 2026-05-10T17:51:28+00:00

I was looking at the Ruby logging library Logging.logger method and have a question

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I was looking at the Ruby logging library Logging.logger method and have a question from the source at github relating to this piece of code:

  logger = ::Logging::Logger.new(name)   logger.add_appenders appender   logger.additive = false    class << logger     def close       @appenders.each {|a| a.close}       h = ::Logging::Repository.instance.instance_variable_get :@h       h.delete(@name)       class << self; undef :close; end     end   end

I understand that the class << logger opens up the eigen/meta/singleton class to the logger object to add an instance specifice close method. However, I am not exactly sure what the ‘class << self; undef :close; end’ does and for what purpose. Can anyone tell me what it means?

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1 Answer

  1. this actually deletes the method (when it actually gets executed). It’s a safeguard to make sure close is not called twice. It kind of looks like there are nested ‘class << ‘ constructs, but there aren’t. The inner class << is executed when the method is called and the outer class << is called when the method is defined.

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