1. Ruby Kanazawa.rb #7 13331

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8. Ruby 313331

9. Ruby NoMethodError: undefined method `XXX for nil:NilClass 313331

10. Ruby NoMethodError: undefined method `XXX for nil:NilClass 1 313331

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19. XML handlerole XML 613331

20. Nokogiri http://nokogiri.org/ XML/HTML XPATH/CSS3 gem install nokogiri 713331

21. 1 require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role").value == "staff" puts " =>staff" end } 813331

22. xml members () => [#, # ] >, #, # ] >, # ] >] Role 913331

23. 1 require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role").value == "staff" puts " =>staff" end } 1013331

24. 1 % ruby xml.rb wtnabe =>staff libero =>staff kiyohara xml.rb:9:in `block in : undefined method `value for nil:NilClass (NoMethodError) from /Users/izawa/.rvm/gems/ruby-2.0.0-p0/gems/ nokogiri-1.5.9/lib/nokogiri/xml/node_set.rb:239:in `block in each : : 1113331

25. 2 require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role") && member.attribute("role").value == "staff" puts " =>staff" end } 1213331

26. 2 % ruby xml.rb wtnabe =>staff libero =>staff kiyohara % 1313331

27. try Object#try NilClass#try active_support argumentblock Person.try(:nd, 1) @people.try(:collect) {|p| p.name} @person.try { |p| p "#{p.rst_name#{p.last_name}" } Object#send NoMethodError exception nil 1413331

28. try require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role") && member.attribute("role").value == "staff" puts " =>staff" end } 1513331

29. try require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role").try(:value) == "staff" puts " =>staff" end } 1513331

30. try require nokogiri xml = Nokogiri::XML(open("kzrb.xml")) members = xml.xpath("//member") members.each { |member| puts member.attribute("handle").value if member.attribute("role").try(:value) == "staff" puts " =>staff" end } 1513331

31. active_support 2.x require active_support active_support 3.x require active_support/core_ext ( active_support/all) 1613331

32. Thank You! If you have any comments, please send to: Mail: izawa@izawa.org / izawa@clwit.co.jp Twitter: @Yukimitsu_Izawa 1713331