7 ms·

Extreme isolation in web apps

19 points by patchfx 13y ago

stiff 13y ago
This must be the Ruby equivalent of the once prevalent Java pattern craze, I mean what the hell is the purpose of a class like this: class JoiningError < Struct.new(:message) def effect(caller) caller.joining_error(self) end end
- chrismdp 13y ago
  The purpose is to avoid a big case statement: case(change.class) when JoiningError: joining_error() when SomethingElse: something_else() ... end It's actually not implemented like that under the hood: it's done using a module with a `send`.
  - stiff 13y ago
    I don't get it at all. Here is the whole thing in straightforward 80's OOP: post '/join/?' do game_server = GameServer.instance if game_server.join(params[:name], @account.id) flash[:notice] = "You have joined the game." redirect_to '/game' else flash[:error] = "There was an error when joining: #{change.message}" haml :join end end class GameServer include Singleton def initialize @games = [Game.new] end def join(name, account_id) player = Player.new(name, account_id) return @games.last.joined_by(player) end end class Player < Struct.new(:name, :account_id) end class Game def initialize @players = [] @events = [] end def joined_by(player) if @players.none? { |player| player.name == player.name } @players << player @events << PlayerJoined.new return true else @events << JoiningError.new return false end end end class Event end class PlayerJoined < Event end class JoiningError < Event end Could you explain to me how is the version presented an improvement over such a straightforward one?
    - chrismdp 13y ago
      There's no persistence in your example: how would you plug that in?
      - stiff 13y ago
        If I would see any purpose in striving for this level of separation I would use the DataMapper pattern (http://martinfowler.com/eaaCatalog/dataMapper.html http://martinfowler.com/eaaCatalog/dataMapper.html), but I do not see it, so the Player etc. models would probably be ActiveRecords.
        chrismdp 13y ago
        I've written lots of web apps using the plain ActiveRecord approach, and I've found it scales well to a given level of complexity, and then becomes hard to manage - hence trying something different.

19 points by patchfx 13y ago

stiff 13y ago

This must be the Ruby equivalent of the once prevalent Java pattern craze, I mean what the hell is the purpose of a class like this: class JoiningError < Struct.new(:message) def effect(caller) caller.joining_error(self) end end

chrismdp 13y ago
The purpose is to avoid a big case statement: case(change.class) when JoiningError: joining_error() when SomethingElse: something_else() ... end It's actually not implemented like that under the hood: it's done using a module with a `send`.
- stiff 13y ago
  I don't get it at all. Here is the whole thing in straightforward 80's OOP: post '/join/?' do game_server = GameServer.instance if game_server.join(params[:name], @account.id) flash[:notice] = "You have joined the game." redirect_to '/game' else flash[:error] = "There was an error when joining: #{change.message}" haml :join end end class GameServer include Singleton def initialize @games = [Game.new] end def join(name, account_id) player = Player.new(name, account_id) return @games.last.joined_by(player) end end class Player < Struct.new(:name, :account_id) end class Game def initialize @players = [] @events = [] end def joined_by(player) if @players.none? { |player| player.name == player.name } @players << player @events << PlayerJoined.new return true else @events << JoiningError.new return false end end end class Event end class PlayerJoined < Event end class JoiningError < Event end Could you explain to me how is the version presented an improvement over such a straightforward one?
  - chrismdp 13y ago
    There's no persistence in your example: how would you plug that in?
    - stiff 13y ago
      If I would see any purpose in striving for this level of separation I would use the DataMapper pattern (http://martinfowler.com/eaaCatalog/dataMapper.html http://martinfowler.com/eaaCatalog/dataMapper.html), but I do not see it, so the Player etc. models would probably be ActiveRecords.
      - chrismdp 13y ago
        I've written lots of web apps using the plain ActiveRecord approach, and I've found it scales well to a given level of complexity, and then becomes hard to manage - hence trying something different.