Vilnius Ruby Masters

Theory VS Reality

Dangers and how to avoid them

CSS: global selectors

img { border: 5px; }
VS 
.fancy-image { border: 5px; }

CSS: global selectors

img { border: 5px; }
VS 
.fancy-image { border: 5px; }

HTML: machine readable
VS

Principle of least astonishment (POLA)


              def display_status(log, options)
                if log.pop == 'party: started'
                  options[:party] = true
                end
                print_event_info(options)
              end
            

              def display_status(log, options)
                if log.first == 'party: started'
                  options = options.merge(party: true)
                end
                print_event_info(options)
              end

Ruby: fancy caching


              def calculate_or_return_fast
                @result ||= very_sloooow_calculation
              end
            

              def very_sloooow_calculation
                result = do_some_heavy_work_here
                result > 0 ? result : nil
              end

Ruby: constants


              class User
                OLDEST_LOG_DATE = (Date.today - 7)

                def clean_old_logs
                  Logs.older_than(OLDEST_LOG_DATE).delete_all
                end
              end
            

              class User
                def clean_old_logs
                  Logs.older_than(self.class.oldest_log_date).delete_all
                end

                def self.oldest_log_date
                  (Date.today - 7)
                end
              end

Ruby: getter VS instance var


              def initialize
                @users = [User.new]
              end

              def do_something
                foo(@users) if @users.first.active?
              end
            

              def users
                @user ||= [User.new] # i can change it to [AdminUser.new]
              end

              def do_something
                foo(users) if users.first.active?
              end

GIT: to big PR

OOP: naming


              # calculates active user friends count
              def calculate_value
                users.select(&:active).map { |user| user.friends.count }.sum
              end
            

              def active_users_friends_count
                users.select(&:active).map { |user| user.friends.count }.sum
              end

Our mistakes

Where are we now?

What will happen next?

  • We will continue theodinproject
  • We will meet every week
  • We will have ruby exam
  • We will have Linkedin status updates

kthxbai