Merge branch 'master' into flyweight

README.md

@@ -26,6 +26,7 @@ The goal is to have a set of [GOF patterns](http://www.blackwasp.co.uk/gofpatter
   - [Bridge](structural/bridge.cr)
   - [Composite](structural/composite.cr)
   - [Decorator](structural/decorator.cr)
+  - [Facade](structural/facade.cr)
 
 ## Contribution
 

structural/facade.cr

@@ -0,0 +1,68 @@
+# The facade pattern is a design pattern that is used to simplify access
+# to functionality in complex or poorly designed subsystems.
+# The facade class provides a simple, single-class interface that hides
+# the implementation details of the underlying code.
+
+# ----------------- Complex or poorly designed library -----------------------
+class Arena
+  @round : Round?
+
+  property round
+
+  def initialize(@name : String)
+    load_arena(@name)
+  end
+
+  def load_arena(name : String)
+    puts "Loading arena #{name} from disk..."
+  end
+end
+
+class RoundManager
+  def define_round(arena : Arena, round_params : RoundParams)
+    check_round_params(round_params)
+    arena.round = Round.create_with_params(round_params)
+  end
+
+  def check_round_params(params : RoundParams)
+    puts "Checking validity of round parameters..."
+  end
+end
+
+class Round
+  def initialize(@time : Int32, @matches : Int32)
+    puts "Round initialized with duration #{@time}s and #{@matches} matches."
+  end
+
+  def self.create_with_params(params : RoundParams)
+    Round.new(params.time, params.matches)
+  end
+end
+
+struct RoundParams
+  property time, matches
+
+  def initialize(@time : Int32, @matches : Int32)
+  end
+end
+
+# ----------------------------------------------------------------------------
+
+# Facade provides simplified access to the complex API
+class Facade
+  DEFAULT_TIME    = 60
+  DEFAULT_MATCHES =  3
+
+  def self.create_default_arena : Arena
+    arena = Arena.new("default")
+    rm = RoundManager.new
+    params = RoundParams.new(DEFAULT_TIME, DEFAULT_MATCHES)
+    rm.define_round(arena, params)
+    arena
+  end
+end
+
+Facade.create_default_arena
+# Loading arena default from disk...
+# Checking validity of round parameters...
+# Round initialized with duration 60s and 3 matches.