Convenient logging methods

log_methods.rb

# Author:  Erik Elmore <erik@erikelmore.com>
# License:  Public Domain

# Convenience in logging
module LogMethods
  def error( *args, &blk )
    log :error, *args, &blk
  end
  private :error
  
  def warning( *args, &blk )
    log :warning, *args, &blk
  end
  private :warning
  
  def info( *args, &blk )
    log :info, *args, &blk
  end
  private :info
  
  def debug( *args, &blk )
    log :debug, *args, &blk
  end
  private :debug
  
  def log_context
    self.class
  end
  private :log_context
  
  def log( level, msg = yield )
    raise ArgumentError, 'No message given' if msg.nil? || msg.empty?
    log_write level, '[%s]: %s' % [log_context, msg]
  end
  private :log
  
  def log_write( level, msg )
    puts '%s %s' % [level.to_s.upcase, msg]
  end
  private :log_write
end

# Demonstration
if $0 == __FILE__
  module Test
    class Base
      include LogMethods
      def test
        [:error, :warning, :info, :debug].each{ |m|
          send m,  'Normal'
          send(m){ 'Block (lazy-evaluated)' }
        }
      end
    end
    
    Noisy = Class.new Base
    class Quiet < Base
      def warning(*); end
      def info(*); end
      def debug(*); end
    end
    
    [Noisy, Quiet].each{ |c|
      puts '*** %s' % c
      c.new.test
      puts
    }
  end
end