Debug with Logger

An introductory talk on using the Logger from the Ruby standard lib. vs. `puts` style debugging. Presented at denver.rb.

Transcript

1. Debug logger with
2. hi@lyonsinbeta.com
3. Puts
4. def sort_and_reverse(array) array.sort array.reverse array end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
5. def sort_and_reverse(array) puts "Array: #{array}" array.sort puts "Array after sort, before reverse: #{array}" array.reverse puts "Array after sort and reverse: #{array}" end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
6. def sort_and_reverse(array) sorted = array.sort reverse_sorted = sorted.reverse reverse_sorted end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
7. Logger
8. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::DEBUG @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
9. ... def sort_and_reverse(array) MyLog.log.debug "Array: #{array}" array.sort MyLog.log.debug "After sort method: #{array}" array.reverse MyLog.log.debug "After reverse method: #{array}" array end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
10. ... def sort_and_reverse(array) MyLog.log.debug "Array: #{array}" sorted = array.sort MyLog.log.debug "After sort method: #{sorted}" reverse_sorted = sorted.reverse MyLog.log.debug "After reverse method: #{reverse_sorted}" reverse_sorted end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
11. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
12. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
13. ... def sort_and_reverse(array) MyLog.log.debug "Array: #{array}" sorted = array.sort MyLog.log.debug "After sort method: #{sorted}" reverse_sorted = sorted.reverse MyLog.log.debug "After reverse method: #{reverse_sorted}" reverse_sorted end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
14. What is logging?
15. The Logger class provides a simple but sophisticated logging utility that you can use to output messages. The messages have associated levels, such as INFO or ERROR that indicate their importance. You can then give the Logger a level, and only messages at that level or higher will be printed. http://www.ruby-doc.org/stdlib-2.1.3/libdoc/logger/rdoc/Logger.html
16. A record of stuff that happened.
17. LOG FILES
18. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
19. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new ‘log.txt’ @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
21. Level
22. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
23. UNKNOWN FATAL ERROR WARN INFO DEBUG
24. UNKNOWN FATAL ERROR WARN INFO DEBUG
25. UNKNOWN FATAL ERROR WARN INFO DEBUG
26. UNKNOWN FATAL ERROR WARN INFO DEBUG
27. UNKNOWN FATAL ERROR WARN INFO DEBUG
28. UNKNOWN FATAL ERROR WARN INFO DEBUG
29. Timestamp
30. require 'logger' class MyLog def self.log if @logger.nil? @logger = Logger.new STDOUT @logger.level = Logger::INFO @logger.datetime_format = '%Y-%m-%d %H:%M:%S ' end @logger end end
31. Message
32. ... def sort_and_reverse(array) MyLog.log.debug "Array: #{array}" sorted = array.sort MyLog.log.debug "After sort method: #{sorted}" reverse_sorted = sorted.reverse MyLog.log.debug "After reverse method: #{reverse_sorted}" reverse_sorted end nums = [4, 7, 23, 1, 8, 3, 8, 42, 6] sar_nums = sort_and_reverse nums puts "The original order is: #{nums}" puts "The sorted and reversed order is: #{sar_nums}"
33. Stop using puts to debug
34. Stop using puts to debug Use logger
35. Stop using puts to debug Use logger Debug like a champ
36. Thank you