How to write good code.

My presentation at VarnaConf.
Code from the presentation: https://github.com/RStankov/varna-conf-2012
Video from the presentation: https://www.youtube.com/watch?v=avhljVTlHZE

Transcript

1. Radoslav Stankov
   VarnaConf 11/08/2012
   How to write good code
   

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2. How am I?
   @rstankov
   http://rstankov.com
   http://github.com/rstankov
   

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9. Huey
   

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10. Huey Dewey
    

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11. Huey Dewey Louie
    

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14. 
    
    Section 1
    
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    ...
    
    
    
    

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15. $('.accordion-menu .item a').each(function() {
    $(this).bind('click', function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    } else {
    }
    });
    });
    

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16. $('.accordion-menu .item a').each(function() {
    $(this).bind('click', function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    } else {
    }
    });
    });
    

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17. $('.accordion-menu .item a').each(function() {
    $(this).bind('click', function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    });
    

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18. $('.accordion-menu .item a').each(function() {
    $(this).bind('click', function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    });
    

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19. $('.accordion-menu .item a').click(function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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20. $('.accordion-menu .item a').click(function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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21. 
    
    Section 1
    
    ...
    ...
    ...
    
    
    
    

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22. 
    
    Section 1
    
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23. 
    
    Section 1
    
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24. 
    
    Section 1
    
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25. 
    
    Section 1
    
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    ...
    
    
    
    

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26. $('.accordion-menu .item a').click(function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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27. $('.accordion-menu .item a').click(function() {
    var title = this.className;
    var theul = $('#' + title);
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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28. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul');
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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29. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul');
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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30. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul');
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    } else {
    theul.slideUp();
    var theli = dropa.parent('li');
    theli.animate({'padding-bottom': '20px'});
    }
    }
    });
    

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31. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul');
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    var theli = dropa.parent('li')
    theli.animate({'padding-bottom': '20px'});
    }
    });
    

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32. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul');
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    var theli = dropa.parent('li')
    theli.animate({'padding-bottom': '20px'});
    }
    });
    

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33. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    }
    });
    

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34. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    if (theul.css('display') == 'none') {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    }
    });
    

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35. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    if (theul.is(':visible')) {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    }
    });
    

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36. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    if (theul.is(':visible')) {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    }
    });
    

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37. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    if (theul.is(':visible')) {
    theul.slideDown()
    } else {
    theul.slideUp()
    }
    }
    });
    

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38. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    theul.slideToggle();
    }
    });
    

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39. $('.accordion-menu .item a').click(function() {
    var theul = $(this).next('ul')
    if (theul.length > 0) {
    theul.slideToggle();
    }
    });
    

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40. $('.accordion-menu .item a').click(function() {
    $(this).next('ul').slideToggle();
    });
    

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41. $('.accordion-menu .item a').click(function() {
    $(this).next('ul').slideToggle();
    });
    

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42. $('.accordion-menu .item a').click(function() {
    $(this).next('ul').slideToggle();
    });
    

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43. $('.accordion-menu .item a').live('click', function() {
    $(this).next('ul').slideToggle();
    });
    

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44. $('.accordion-menu .item a').live('click', function() {
    $(this).next('ul').slideToggle();
    });
    

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45. $('.accordion-menu .item a').live('click', function() {
    $(this).next('ul').slideToggle();
    });
    

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46. $('.accordion-menu .item a').click(function() {
    $(this).next('ul').slideToggle();
    });
    

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47. $(document).on('click', '.accordion-menu .item a', function() {
    $(this).next('ul').slideToggle();
    });
    

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48. $(document).on('click', '.js-accordion-item a', function() {
    $(this).next('js-accordion-section').slideToggle();
    });
    

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49. $(document).on('click', '[data-accordion="item"]', function() {
    $(this).next('[data-accordion="section"]').slideToggle();
    });
    

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50. Know your tools
    

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51. View Slide

52. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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53. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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54. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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55. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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56. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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57. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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58. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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59. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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60. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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61. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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62. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    Copy
    &
    Paste
    

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63. class MostLikedFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('votes_count')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    MostLikedFriendImages.new(current_user).images(params[:page])
    

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64. class MostLikedFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('votes_count')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    MostLikedFriendImages.new(current_user).images(params[:page])
    

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65. class MostLikedFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('votes_count')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    MostLikedFriendImages.new(current_user).images(params[:page])
    

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66. class MostLikedFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('votes_count')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    MostLikedFriendImages.new(current_user).images(params[:page])
    

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67. class MostLikedFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('votes_count')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    MostLikedFriendImages.new(current_user).images(params[:page])
    

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68. DRY
    don’t repeat yourself
    

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69. Every piece of knowledge must have
    a single, unambiguous, authoritative
    representation within a system.
    

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70. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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71. class NewsestFriendImages
    def initialize(user)
    @user = user
    end
    def images(page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order('created_at')
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    NewsestFriendImages.new(current_user).images(params[:page])
    

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72. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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73. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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74. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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75. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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76. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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77. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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78. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    FriendImages.new(current_user).images('created_at', params[:page])
    FriendImages.new(current_user).images('likes_count', params[:page])
    

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79. The bad side of DRY
    

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80. http://bit.ly/O5jSLV
    

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81. API_GET = '/api/:source_type/:id'
    API_GET_DETAILS = '/api/:source_type/:id/details'
    API_GET_VERSION = '/api/:source_type/:id/on/:year/:date/:month'
    API_GET_SUBTYPE = '/api/:source_type/:id/sub/:subtype/:subtype_id'
    

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82. API = 'api'
    SOURCE_TYPE = '/:source_type'
    SOURCE_ID = '/:id'
    SOURCE_DATE = '/:year/:month/:day'
    SUBTYPE = '/:subtype'
    SUBID = '/:subtype_id'
    API_GET = API + SOURCE_TYPE + SOURCE_ID
    API_GET_DETAILS = API + SOURCE_TYPE + SOURCE_ID + '/details'
    API_GET_VERSION = API + SOURCE_TYPE + SOURCE_ID + '/on' + SOURCE_DATE
    API_GET_SUBTYPE = API + SOURCE_TYPE + SOURCE_ID + '/sub' + SUBTYPE + SUBID
    

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83. def api_path(rest = '')
    BASE_PATH + rest
    end
    def token(string)
    SEPARATOR + string
    end
    SEPARATOR = '/'
    API = 'api'
    SOURCE_TYPE = ':source_type'
    SOURCE_ID = ':id'
    YEAR = ':year'
    MONTH = ':month'
    DAY = ':day'
    SUBTYPE = ':subtype'
    SUBID = ':subtype_id'
    DETAILS = 'details'
    ON = 'on'
    SUB = 'sub'
    BASE_PATH = token(API) + token(SOURCE_TYPE) + token(SOURCE_ID)
    DATE_PART = token(YEAR) + token(MONTH) + token(DAY)
    SUB_PART = token(SUBTYPE) + token(SUBID)
    API_GET = api_path()
    API_GET_DETAILS = api_path(token(DETAILS))
    API_GET_VERSION = api_path(token(ON) + token(DATE_PART))
    API_GET_SUBTYPE = api_path(token(SUB) + token(SUB_PART))
    

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84. View Slide

85. View Slide

86. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    

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87. SLAP
    Single Level of Abstraction Principle
    

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88. Keep all lines of code in a method at
    the same level of abstraction.
    

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89. class FriendImages
    def initialize(user)
    @user = user
    end
    def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    end
    

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90. def images(sorting, page)
    friends = Friendship.where(user_id: @user.id).pluck('friend_id')
    images = Image.where(user_id: friends, visible_to_friends: true)
    images = images.where('minimum_age >= ?', @user.age)
    images = images.order(sorting)
    images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    images.map { |image| ImageDecorator.new(image) }
    end
    

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91. def images(sorting, page)
    images = find_images_of(friends)
    images = apply_age_restritions_to(images)
    images = order_by(images, sorting)
    images = paginate(images, page)
    decorate(images)
    end
    

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92. def friends
    Friendship.where(user_id: @user.id).pluck('friend_id')
    end
    def find_images_of(friends)
    Image.where(user_id: friends, visible_to_friends: true)
    end
    def apply_age_restritions_to(images)
    images.where('minimum_age >= ?', @user.age)
    end
    def order_by(sorting)
    images.order(sorting)
    end
    def paginate(page)
    images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    end
    def decorate(images)
    images.map { |image| ImageDecorator.new(image) }
    end
    

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93. Law of Demeter
    

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94. • You can play with yourself.
    • You can play with your own toys (but you can't
    take them apart),
    • You can play with toys that were given to you.
    • And you can play with toys you've made
    yourself.
    

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95. • Your method can call other methods in its
    class directly
    • Your method can call methods on its own
    fields directly (but not on the fields' fields)
    • When your method takes parameters, your
    method can call methods on those parameters
    directly.
    • When your method creates local objects, that
    method can call methods on the local objects.
    

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96. def friends
    Friendship.where(user_id: @user.id).pluck('friend_id')
    end
    def find_images_of(friends)
    Image.where(user_id: friends, visible_to_friends: true)
    end
    def apply_age_restritions_to(images)
    images.where('minimum_age >= ?', @user.age)
    end
    def order_by(sorting)
    images.order(sorting)
    end
    def paginate(page)
    images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
    end
    def decorate(images)
    images.map { |image| ImageDecorator.new(image) }
    end
    

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97. def friends
    Friendship.friend_ids_of(@user)
    end
    def find_images_of(friends)
    Image.of(friends)
    end
    def apply_age_restritions_to(images)
    images.appropriate_for(@user.age)
    end
    def order_by(sorting)
    images.order(sorting)
    end
    def paginate(page)
    images.paginate(page)
    end
    def decorate(images)
    images.map { |image| ImageDecorator.new(image) }
    end
    

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98. def images(sorting, page)
    images = find_images_of(friends)
    images = apply_age_restritions_to(images)
    images = order_by(images, sorting)
    images = paginate(images, page)
    decorate(images)
    end
    

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99. def images(sorting, page)
    decorate Image
    .of(friends)
    .appropriate_for(@user.age)
    .order(sorting)
    .paginate(page)
    end
    

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100. def images(page)
     friends = Friendship.where(user_id: @user.id).pluck('friend_id')
     images = Image.where(user_id: friends, visible_to_friends: true)
     images = images.where('minimum_age >= ?', @user.age)
     images = images.order('created_at')
     images = images.limit(PER_PAGE).offset(page.to_i.abs * PER_PAGE)
     images.map { |image| ImageDecorator.new(image) }
     end
     

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101. def images(sorting, page)
     decorate Image
     .of(friends)
     .appropriate_for(@user.age)
     .order(sorting)
     .paginate(page)
     end
     

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102. Code smells
     

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103. • Duplicated Code
     • Long Method
     • Large Class
     • Long Parameter List
     • Shotgun Surgery
     • Feature Envy
     • Data Clumps
     • Case Statements
     • Parallel Inheritance Hierarchies
     • Speculative Generality
     • Temporary Field
     • Message Chains
     • Middle Man
     • Alternative Classes with Different Interfaces
     • Refused Bequest
     • Comments
     • Repetitive Boilerplate
     • и т.н....
     

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104. Refactoring:
     Improving the Design of Existing Code.
     Martin Fowler
     

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105. Out side of the box
     

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106. Retrospection
     

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107. Retrospection
     ✓ DRY
     

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108. Retrospection
     ✓ DRY
     ✓ SLAP
     

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109. Retrospection
     ✓ DRY
     ✓ SLAP
     ✓ Law of demeter
     

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110. Retrospection
     ✓ DRY
     ✓ SLAP
     ✓ Law of demeter
     ✓ Tools
     

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111. Retrospection
     ✓ DRY
     ✓ SLAP
     ✓ Law of demeter
     ✓ Tools
     ✓ Code smells
     

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112. Retrospection
     ✓ DRY
     ✓ SLAP
     ✓ Law of demeter
     ✓ Tools
     ✓ Code smells
     ✓ Out side the box
     

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113. View Slide

114. Code, step by step
     https://github.com/RStankov/varna-conf-2012
     

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115. View Slide

116. @rstankov
     Thanks for listening :)
     

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117. Questions?
     

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