Changes to the name interface and couple other things:

* Made sure entities added and removed before World:start is called.
* Updated .gitignore for ammo-assets.

.gitignore

@@ -1,6 +1,7 @@
 _*
 .DS_STORE
 .DS_Store
+assets/
 tweens/
 physics/
 input/

core/Entity.lua

@@ -29,9 +29,8 @@ function Entity._mt:__newindex(key, value)
     if self._name == value then return end
 
     if self._world then
-      local prev = self._name
-      self._name = value
-      self._world:_setName(self, prev)
+      if self._name then self._world.names[self._name] = nil end
+      self._world.names[value] = self
     else
       self._name = value
     end

core/World.lua

@@ -42,7 +42,15 @@ function World:initialize()
   self._add = {}
   self._remove = {}
   self._classCounts = {}
-  self.names = {}
+  self._names = setmetatable({}, { __newindex = function(s, k, v) print(k, v); rawset(s, k, v) end })
+
+  -- interface to _names
+  self.names = setmetatable({}, { __index = self._names, __newindex = function(_, name, entity)
+    if self._names[name] then self._names[name]._name = nil end
+    self._names[name] = entity
+    --print(name, entity, self._names)
+    if entity then entity._name = name end
+  end })
 
   self:applyAccessors()
   self.camera = nil -- set off the default behaviour
@@ -162,8 +170,8 @@ function World:_updateLists()
     v._removalQueued = false
     v._world = nil
     if v.class then self._classCounts[v.class.name] = self._classCounts[v.class.name] - 1 end
-    if v.layer then self._layers[v._layer]:remove(v) end
-    if v.name then self.names[v.name] = nil end 
+    if v._layer then self._layers[v._layer]:remove(v) end
+    if v._name then self._names[v._name] = nil end 
   end
 
   -- add
@@ -172,8 +180,8 @@ function World:_updateLists()
     v._additionQueued = false
     v._world = self
     if v.class then self._classCounts[v.class.name] = (self._classCounts[v.class.name] or 0) + 1 end
-    if v.layer then self:_setLayer(v) end
-    if v.name then self:_setName(v) end
+    if v._layer then self:_setLayer(v) end
+    if v._name then self.names[v._name] = v end
     if v.added then v:added() end
   end
 
@@ -187,9 +195,3 @@ function World:_setLayer(e, prev)
   if not self._layers[e.layer] then self:addLayer(e.layer) end
   self._layers[e.layer]:unshift(e)
 end
-
-function World:_setName(e, prev)
-  assert(not self.names[e.name], "An entity already has the name \"" .. e.name .. "\" in this world.")
-  if prev then self.names[prev] = nil end
-  self.names[e.name] = e
-end

core/init.lua

@@ -40,7 +40,11 @@ function ammo.update(dt)
     if ammo._world then ammo._world:stop() end
     ammo._world = ammo._goto
     ammo._goto = nil
-    if ammo._world then ammo._world:start() end
+
+    if ammo._world then
+      ammo._world:_updateLists() -- make sure all entities are added (or removed) beforehand
+      ammo._world:start()
+    end
   end
 end