Data commit

Task/Delegates/Lua/delegates.lua

@@ -0,0 +1,46 @@
+local function Delegator()
+  return {
+    operation = function(self)
+      if (type(self.delegate)=="table") and (type(self.delegate.thing)=="function") then
+        return self.delegate:thing()
+      else
+        return "default implementation"
+      end
+    end
+  }
+end
+
+local function Delegate()
+  return {
+    thing = function(self)
+      return "delegate implementation"
+    end
+  }
+end
+
+local function NonDelegate(which)
+  if (which == 1) then return true -- boolean
+  elseif (which == 2) then return 12345 -- number
+  elseif (which == 3) then return "Hello" -- string
+  elseif (which == 4) then return function() end -- function
+  elseif (which == 5) then return { nothing = function() end } -- table (without "thing")
+  elseif (which == 6) then return coroutine.create(function() end) -- thread
+  elseif (which == 7) then return io.open("delegates.lua","r") -- userdata (if exists, or nil)
+  end
+end
+
+-- WITH NO (NIL) DELEGATE
+local d = Delegator()
+assert(d:operation() == "default implementation")
+
+-- WITH A NON-DELEGATE
+for i = 1, 7 do
+  d.delegate = NonDelegate(i)
+  assert(d:operation() == "default implementation")
+end
+
+-- WITH A PROPER DELEGATE
+d.delegate = Delegate()
+assert(d:operation() == "delegate implementation")
+
+print("pass")