Logging::Logger #with_backtrace

Logging::Logger.rb

# https://github.com/TwP/logging/
# Temporarily log with or without backtrace
#
# Usage:
# require 'logging'
# logger = Logging.logger(STDOUT)
# logger.with_backtrace do
#   logger.error StandardError.new('oups!')
# end
#
module Logging
  class Logger
    # force backtrace logging temporarily
    def with_backtrace(&block)
      self.class.send(:_backtrace_backup, self)
      self.class.send(:_backtrace_on, self)
      yield block
    ensure
      self.class.send(:_backtrace_restore, self)
    end
    
    # force no backtrace logging temporarily
    def without_backtrace(&block)
      self.class.send(:_backtrace_backup, self)
      self.class.send(:_backtrace_off, self)
      yield block
    ensure
      self.class.send(:_backtrace_restore, self)
    end

    def self._backtrace_backup(logger)
      @_appenders ||= {}

      logger.appenders.each_with_object(@_appenders) do |appender, accu|
        accu[appender.object_id] = appender.layout.instance_variable_get(:@backtrace)
      end

      _backtrace_backup(logger.parent) if logger.respond_to? :parent
    end
    private_class_method :_backtrace_backup

    def self._backtrace_restore(logger)
      appenders = logger.instance_variable_get(:@appenders)
      logger.appenders.clear

      appenders.each do |appender|
        appender.layout.instance_variable_set(:@backtrace, @_appenders[appender.object_id])
      end

      _backtrace_restore(logger.parent) if logger.respond_to? :parent
    end
    private_class_method :_backtrace_restore

    def self._backtrace_off(logger)
      logger.instance_variable_get(:@appenders).each do |appender|
        appender.layout.instance_variable_set(:@backtrace, false)
      end

      _backtrace_off(logger.parent) if logger.respond_to? :parent
    end
    private_class_method :_backtrace_off

    def self._backtrace_on(logger)
      logger.instance_variable_get(:@appenders).each do |appender|
        appender.layout.instance_variable_set(:@backtrace, true)
      end

      _backtrace_on(logger.parent) if logger.respond_to? :parent
    end
    private_class_method :_backtrace_on
  end
end